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  • Review Article
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Structural insights into the catalysis and regulation of E3 ubiquitin ligases

Key Points

  • Ubiquitin ligases (E3s) recruit ubiquitin-conjugating enzyme (E2)ubiquitin ( denotes a thioester linkage; here, the linkage is between the catalytic cysteine of E2 and the carboxyl terminus of ubiquitin) complexes and a substrate to promote ubiquitin transfer onto the substrate.

  • The mechanisms of catalysis and regulation of three classes of E3s identified to date — RING (really interesting new gene), HECT (homologous to E6AP C terminus) and RBR (RING-between-RING) — are summarized in this Review.

  • Crystal structures and nuclear magnetic resonance studies have revealed that RING E3s prime E2ubiquitin for transfer by promoting a closed E2ubiquitin conformation in which the thioester is activated towards nucleophilic attack onto the substrate lysine.

  • Crystal structures of HECT E3s in different stages of catalysis have revealed that conformational changes juxtapose reactants (catalytic cysteine residues of E2 and E3 as well as the catalytic cysteine of E3 and the target residue of the substrate) to prime ubiquitin transfer.

  • Crystal structures have revealed how RBR E3s are autoinhibited in solution. Upon activation, crystal structures of RBR E3s bound to E2ubiquitin have shown how ubiquitin is transferred from E2 to E3 and subsequently to the substrate.

  • Substrate lysine selection and the outcome of ubiquitylation depend on spatial arrangements within E2-E3-substrate complexes. Substrate lysine residues that are in proximity to the active sites of E2 or E3 are prioritized for ligation.

  • E3s are regulated by various autoinhibitory mechanisms that hinder their catalytic cycle. Activation frequently requires post-translational modification or binding of protein partners or substrates.

Abstract

Covalent attachment (conjugation) of one or more ubiquitin molecules to protein substrates governs numerous eukaryotic cellular processes, including apoptosis, cell division and immune responses. Ubiquitylation was originally associated with protein degradation, but it is now clear that ubiquitylation also mediates processes such as protein–protein interactions and cell signalling depending on the type of ubiquitin conjugation. Ubiquitin ligases (E3s) catalyse the final step of ubiquitin conjugation by transferring ubiquitin from ubiquitin-conjugating enzymes (E2s) to substrates. In humans, more than 600 E3s contribute to determining the fates of thousands of substrates; hence, E3s need to be tightly regulated to ensure accurate substrate ubiquitylation. Recent findings illustrate how E3s function on a structural level and how they coordinate with E2s and substrates to meticulously conjugate ubiquitin. Insights regarding the mechanisms of E3 regulation, including structural aspects of their autoinhibition and activation are also emerging.

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Figure 1: The ubiquitin conjugation system.
Figure 2: E3 catalytic mechanisms.
Figure 3: Mechanism of priming ubiquitin for transfer by RING E3s.
Figure 4: Mechanism of ubiquitin transfer by HECT E3s.
Figure 5: Mechanism of ubiquitin transfer by RBR E3s.
Figure 6: Mechanisms of substrate lysine selection.
Figure 7: Mechanisms of autoinhibition and activation of E3s.

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References

  1. Hershko, A. & Ciechanover, A. The ubiquitin system. Annu. Rev. Biochem. 67, 425–479 (1998).

    CAS  PubMed  Google Scholar 

  2. Dye, B. T. & Schulman, B. A. Structural mechanisms underlying posttranslational modification by ubiquitin-like proteins. Annu. Rev. Biophys. Biomol. Struct. 36, 131–150 (2007).

    CAS  PubMed  Google Scholar 

  3. Pickart, C. M. & Eddins, M. J. Ubiquitin: structures, functions, mechanisms. Biochim. Biophys. Acta 1695, 55–72 (2004).

    CAS  PubMed  Google Scholar 

  4. Komander, D. & Rape, M. The ubiquitin code. Annu. Rev. Biochem. 81, 203–229 (2012).

    CAS  PubMed  Google Scholar 

  5. Chau, V. et al. A multiubiquitin chain is confined to specific lysine in a targeted short-lived protein. Science 243, 1576–1583 (1989).

    CAS  PubMed  Google Scholar 

  6. Finley, D. Recognition and processing of ubiquitin–protein conjugates by the proteasome. Annu. Rev. Biochem. 78, 477–513 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  7. Haglund, K. & Dikic, I. The role of ubiquitylation in receptor endocytosis and endosomal sorting. J. Cell Sci. 125, 265–275 (2012).

    CAS  PubMed  Google Scholar 

  8. Chen, Z. J. & Sun, L. J. Nonproteolytic functions of ubiquitin in cell signaling. Mol. Cell 33, 275–286 (2009).

    CAS  PubMed  Google Scholar 

  9. Ulrich, H. D. & Walden, H. Ubiquitin signalling in DNA replication and repair. Nat. Rev. Mol. Cell Biol. 11, 479–489 (2010).

    CAS  PubMed  Google Scholar 

  10. Hoege, C., Pfander, B., Moldovan, G. L., Pyrowolakis, G. & Jentsch, S. RAD6-dependent DNA repair is linked to modification of PCNA by ubiquitin and SUMO. Nature 419, 135–141 (2002).

    CAS  PubMed  Google Scholar 

  11. Robzyk, K., Recht, J. & Osley, M. A. Rad6-dependent ubiquitination of histone H2B in yeast. Science 287, 501–504 (2000).

    CAS  PubMed  Google Scholar 

  12. Jin, J., Li, X., Gygi, S. P. & Harper, J. W. Dual E1 activation systems for ubiquitin differentially regulate E2 enzyme charging. Nature 447, 1135–1138 (2007).

    CAS  PubMed  Google Scholar 

  13. Ye, Y. & Rape, M. Building ubiquitin chains: E2 enzymes at work. Nat. Rev. Mol. Cell Biol. 10, 755–764 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  14. Li, W. et al. Genome-wide and functional annotation of human E3 ubiquitin ligases identifies MULAN, a mitochondrial E3 that regulates the organelle's dynamics and signaling. PLoS ONE 3, e1487 (2008).

    PubMed  PubMed Central  Google Scholar 

  15. Levkowitz, G. et al. Ubiquitin ligase activity and tyrosine phosphorylation underlie suppression of growth factor signaling by c-Cbl/Sli-1. Mol. Cell 4, 1029–1040 (1999).

    CAS  PubMed  Google Scholar 

  16. Waterman, H. et al. A mutant EGF-receptor defective in ubiquitylation and endocytosis unveils a role for Grb2 in negative signaling. EMBO J. 21, 303–313 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Mizushima, T. et al. Structural basis for the selection of glycosylated substrates by SCFFbs1 ubiquitin ligase. Proc. Natl Acad. Sci. USA 104, 5777–5781 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  18. Scrima, A. et al. Structural basis of UV DNA-damage recognition by the DDB1–DDB2 complex. Cell 135, 1213–1223 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  19. El-Mahdy, M. A. et al. Cullin 4A-mediated proteolysis of DDB2 protein at DNA damage sites regulates in vivo lesion recognition by XPC. J. Biol. Chem. 281, 13404–13411 (2006).

    CAS  PubMed  Google Scholar 

  20. Sugasawa, K. et al. UV-induced ubiquitylation of XPC protein mediated by UV-DDB–ubiquitin ligase complex. Cell 121, 387–400 (2005).

    CAS  PubMed  Google Scholar 

  21. Deshaies, R. J. & Joazeiro, C. A. RING domain E3 ubiquitin ligases. Annu. Rev. Biochem. 78, 399–434 (2009).

    CAS  PubMed  Google Scholar 

  22. Zheng, N., Wang, P., Jeffrey, P. D. & Pavletich, N. P. Structure of a c-Cbl–UbcH7 complex: RING domain function in ubiquitin–protein ligases. Cell 102, 533–539 (2000).

    CAS  PubMed  Google Scholar 

  23. Dominguez, C. et al. Structural model of the UbcH5B/CNOT4 complex revealed by combining NMR, mutagenesis, and docking approaches. Structure 12, 633–644 (2004).

    CAS  PubMed  Google Scholar 

  24. Buetow, L. et al. Activation of a primed RING E3-E2–ubiquitin complex by non-covalent ubiquitin. Mol. Cell 58, 297–310 (2015).

    CAS  PubMed  Google Scholar 

  25. Mace, P. D. et al. Structures of the cIAP2 RING domain reveal conformational changes associated with ubiquitin-conjugating enzyme (E2) recruitment. J. Biol. Chem. 283, 31633–31640 (2008).

    CAS  PubMed  Google Scholar 

  26. Yin, Q. et al. E2 interaction and dimerization in the crystal structure of TRAF6. Nat. Struct. Mol. Biol. 16, 658–666 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  27. Plechanovova, A. et al. Mechanism of ubiquitylation by dimeric RING ligase RNF4. Nat. Struct. Mol. Biol. 18, 1052–1059 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  28. Brzovic, P. S., Rajagopal, P., Hoyt, D. W., King, M. C. & Klevit, R. E. Structure of a BRCA1–BARD1 heterodimeric RING–RING complex. Nat. Struct. Biol. 8, 833–837 (2001).

    CAS  PubMed  Google Scholar 

  29. Buchwald, G. et al. Structure and E3-ligase activity of the Ring–Ring complex of polycomb proteins Bmi1 and Ring1b. EMBO J. 25, 2465–2474 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  30. Badciong, J. C. & Haas, A. L. MdmX is a RING finger ubiquitin ligase capable of synergistically enhancing Mdm2 ubiquitination. J. Biol. Chem. 277, 49668–49675 (2002).

    CAS  PubMed  Google Scholar 

  31. Linares, L. K., Hengstermann, A., Ciechanover, A., Muller, S. & Scheffner, M. HdmX stimulates Hdm2-mediated ubiquitination and degradation of p53. Proc. Natl Acad. Sci. USA 100, 12009–12014 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  32. Li, Z. et al. Structure of a Bmi-1-Ring1B polycomb group ubiquitin ligase complex. J. Biol. Chem. 281, 20643–20649 (2006).

    CAS  PubMed  Google Scholar 

  33. Micale, L., Chaignat, E., Fusco, C., Reymond, A. & Merla, G. The tripartite motif: structure and function. Adv. Exp. Med. Biol. 770, 11–25 (2012).

    CAS  PubMed  Google Scholar 

  34. Lydeard, J. R., Schulman, B. A. & Harper, J. W. Building and remodelling Cullin–RING E3 ubiquitin ligases. EMBO Rep. 14, 1050–1061 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  35. Petroski, M. D. & Deshaies, R. J. Function and regulation of cullin–RING ubiquitin ligases. Nat. Rev. Mol. Cell Biol. 6, 9–20 (2005).

    CAS  PubMed  Google Scholar 

  36. Chang, L. & Barford, D. Insights into the anaphase-promoting complex: a molecular machine that regulates mitosis. Curr. Opin. Struct. Biol. 29, 1–9 (2014).

    CAS  PubMed  Google Scholar 

  37. Ohi, M. D., Vander Kooi, C. W., Rosenberg, J. A., Chazin, W. J. & Gould, K. L. Structural insights into the U-box, a domain associated with multi-ubiquitination. Nat. Struct. Biol. 10, 250–255 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  38. Tu, D., Li, W., Ye, Y. & Brunger, A. T. Structure and function of the yeast U-box-containing ubiquitin ligase Ufd2p. Proc. Natl Acad. Sci. USA 104, 15599–15606 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  39. Vander Kooi, C. W. et al. The Prp19 U-box crystal structure suggests a common dimeric architecture for a class of oligomeric E3 ubiquitin ligases. Biochemistry 45, 121–130 (2006).

    CAS  PubMed  Google Scholar 

  40. Zhang, M. et al. Chaperoned ubiquitylation—crystal structures of the CHIP U box E3 ubiquitin ligase and a CHIP-Ubc13-Uev1a complex. Mol. Cell 20, 525–538 (2005).

    CAS  PubMed  Google Scholar 

  41. Rotin, D. & Kumar, S. Physiological functions of the HECT family of ubiquitin ligases. Nat. Rev. Mol. Cell Biol. 10, 398–409 (2009).

    CAS  PubMed  Google Scholar 

  42. Huang, L. et al. Structure of an E6AP-UbcH7 complex: insights into ubiquitination by the E2-E3 enzyme cascade. Science 286, 1321–1326 (1999).

    CAS  PubMed  Google Scholar 

  43. Verdecia, M. A. et al. Conformational flexibility underlies ubiquitin ligation mediated by the WWP1 HECT domain E3 ligase. Mol. Cell 11, 249–259 (2003).

    CAS  PubMed  Google Scholar 

  44. Smit, J. J. & Sixma, T. K. RBR E3-ligases at work. EMBO Rep. 15, 142–154 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  45. Spratt, D. E., Walden, H. & Shaw, G. S. RBR E3 ubiquitin ligases: new structures, new insights, new questions. Biochem. J. 458, 421–437 (2014).

    CAS  PubMed  Google Scholar 

  46. Imai, Y., Soda, M. & Takahashi, R. Parkin suppresses unfolded protein stress-induced cell death through its E3 ubiquitin-protein ligase activity. J. Biol. Chem. 275, 35661–35664 (2000).

    CAS  PubMed  Google Scholar 

  47. Zhang, Y. et al. Parkin functions as an E2-dependent ubiquitin-protein ligase and promotes the degradation of the synaptic vesicle-associated protein, CDCrel-1. Proc. Natl Acad. Sci. USA 97, 13354–13359 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  48. Moynihan, T. P. et al. The ubiquitin-conjugating enzymes UbcH7 and UbcH8 interact with RING finger/IBR motif-containing domains of HHARI and H7-AP1. J. Biol. Chem. 274, 30963–30968 (1999).

    CAS  PubMed  Google Scholar 

  49. Shimura, H. et al. Familial Parkinson disease gene product, parkin, is a ubiquitin-protein ligase. Nat. Genet. 25, 302–305 (2000).

    CAS  PubMed  Google Scholar 

  50. Wenzel, D. M., Lissounov, A., Brzovic, P. S. & Klevit, R. E. UBCH7 reactivity profile reveals parkin and HHARI to be RING/HECT hybrids. Nature 474, 105–108 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  51. Ozkan, E., Yu, H. & Deisenhofer, J. Mechanistic insight into the allosteric activation of a ubiquitin-conjugating enzyme by RING-type ubiquitin ligases. Proc. Natl Acad. Sci. USA 102, 18890–18895 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  52. Petroski, M. D. & Deshaies, R. J. Mechanism of lysine 48-linked ubiquitin-chain synthesis by the cullin-RING ubiquitin-ligase complex SCF-Cdc34. Cell 123, 1107–1120 (2005).

    CAS  PubMed  Google Scholar 

  53. Saha, A., Lewis, S., Kleiger, G., Kuhlman, B. & Deshaies, R. J. Essential role for ubiquitin-ubiquitin-conjugating enzyme interaction in ubiquitin discharge from Cdc34 to substrate. Mol. Cell 42, 75–83 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  54. Benirschke, R. C. et al. Molecular basis for the association of human E4B U box ubiquitin ligase with E2-conjugating enzymes UbcH5c and Ubc4. Structure 18, 955–965 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  55. Plechanovova, A., Jaffray, E. G., Tatham, M. H., Naismith, J. H. & Hay, R. T. Structure of a RING E3 ligase and ubiquitin-loaded E2 primed for catalysis. Nature 489, 115–120 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  56. Dou, H., Buetow, L., Sibbet, G. J., Cameron, K. & Huang, D. T. BIRC7–E2 ubiquitin conjugate structure reveals the mechanism of ubiquitin transfer by a RING dimer. Nat. Struct. Mol. Biol. 19, 876–883 (2012). References 55 and 56 provide the first crystal structures of dimeric RING E3 bound to E2ubiquitin in a primed conformation.

    CAS  PubMed  Google Scholar 

  57. Pruneda, J. N. et al. Structure of an E3:E2Ub complex reveals an allosteric mechanism shared among RING/U-box ligases. Mol. Cell 47, 933–942 (2012). Shows that RING/U-box E3s drive E2ubiquitin into a closed conformation that is essential for catalysis.

    CAS  PubMed  PubMed Central  Google Scholar 

  58. Pruneda, J. N., Stoll, K. E., Bolton, L. J., Brzovic, P. S. & Klevit, R. E. Ubiquitin in motion: structural studies of the ubiquitin-conjugating enzymeubiquitin conjugate. Biochemistry 50, 1624–1633 (2011).

    CAS  PubMed  Google Scholar 

  59. Soss, S. E., Klevit, R. E. & Chazin, W. J. Activation of UbcH5cUb is the result of a shift in interdomain motions of the conjugate bound to U-box E3 ligase E4B. Biochemistry 52, 2991–2999 (2013).

    CAS  PubMed  Google Scholar 

  60. Page, R. C., Pruneda, J. N., Amick, J., Klevit, R. E. & Misra, S. Structural insights into the conformation and oligomerization of E2ubiquitin conjugates. Biochemistry 51, 4175–4187 (2012).

    CAS  PubMed  Google Scholar 

  61. Dou, H., Buetow, L., Sibbet, G. J., Cameron, K. & Huang, D. T. Essentiality of a non-RING element in priming donor ubiquitin for catalysis by a monomeric E3. Nat. Struct. Mol. Biol. 20, 982–986 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  62. Branigan, E., Plechanovova, A., Jaffray, E. G., Naismith, J. H. & Hay, R. T. Structural basis for the RING-catalyzed synthesis of K63-linked ubiquitin chains. Nat. Struct. Mol. Biol. 22, 597–602 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  63. Reverter, D. & Lima, C. D. Insights into E3 ligase activity revealed by a SUMO–RanGAP1–Ubc9–Nup358 complex. Nature 435, 687–692 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  64. Scott, D. C. et al. Structure of a RING E3 trapped in action reveals ligation mechanism for the ubiquitin-like protein NEDD8. Cell 157, 1671–1684 (2014). Presents a crystal structure of a RING E3-E2ubiquitin like protein–substrate complex, revealing the mechanism of substrate ligation.

    CAS  PubMed  PubMed Central  Google Scholar 

  65. Koliopoulos, M. G., Esposito, D., Christodoulou, E., Taylor, I. A. & Rittinger, K. Functional role of TRIM E3 ligase oligomerization and regulation of catalytic activity. EMBO J. 35, 1204–1218 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  66. Wickliffe, K. E., Lorenz, S., Wemmer, D. E., Kuriyan, J. & Rape, M. The mechanism of linkage-specific ubiquitin chain elongation by a single-subunit E2. Cell 144, 769–781 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  67. Berndsen, C. E., Wiener, R., Yu, I. W., Ringel, A. E. & Wolberger, C. A conserved asparagine has a structural role in ubiquitin-conjugating enzymes. Nat. Chem. Biol. 9, 154–156 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  68. Yunus, A. A. & Lima, C. D. Lysine activation and functional analysis of E2-mediated conjugation in the SUMO pathway. Nat. Struct. Mol. Biol. 13, 491–499 (2006).

    CAS  PubMed  Google Scholar 

  69. Wright, J. D., Mace, P. D. & Day, C. L. Secondary ubiquitin-RING docking enhances Arkadia and Ark2C E3 ligase activity. Nat. Struct. Mol. Biol. 23, 45–52 (2016).

    CAS  PubMed  Google Scholar 

  70. Das, R. et al. Allosteric activation of E2-RING finger-mediated ubiquitylation by a structurally defined specific E2-binding region of gp78. Mol. Cell 34, 674–685 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  71. Metzger, M. B. et al. A structurally unique E2-binding domain activates ubiquitination by the ERAD E2, Ubc7p, through multiple mechanisms. Mol. Cell 50, 516–527 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  72. Hibbert, R. G., Huang, A., Boelens, R. & Sixma, T. K. E3 ligase Rad18 promotes monoubiquitination rather than ubiquitin chain formation by E2 enzyme Rad6. Proc. Natl Acad. Sci. USA 108, 5590–5595 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  73. Li, S. et al. Insights into ubiquitination from the unique clamp-like binding of the RING E3 AO7 to the E2 UbcH5B. J. Biol. Chem. 290, 30225–30239 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  74. Das, R. et al. Allosteric regulation of E2:E3 interactions promote a processive ubiquitination machine. EMBO J. 32, 2504–2516 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  75. Brzovic, P. S., Lissounov, A., Christensen, D. E., Hoyt, D. W. & Klevit, R. E. A. UbcH5/ubiquitin noncovalent complex is required for processive BRCA1-directed ubiquitination. Mol. Cell 21, 873–880 (2006).

    CAS  PubMed  Google Scholar 

  76. Sakata, E. et al. Crystal structure of UbcH5bubiquitin intermediate: insight into the formation of the self-assembled E2Ub conjugates. Structure 18, 138–147 (2010).

    CAS  PubMed  Google Scholar 

  77. Ranaweera, R. S. & Yang, X. Auto-ubiquitination of Mdm2 enhances its substrate ubiquitin ligase activity. J. Biol. Chem. 288, 18939–18946 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  78. Kamadurai, H. B. et al. Insights into ubiquitin transfer cascades from a structure of a UbcH5Bubiquitin-HECTNEDD4L complex. Mol. Cell 36, 1095–1102 (2009). The first crystal structure of a HECT E3 bound to E2ubiquitin.

    CAS  PubMed  PubMed Central  Google Scholar 

  79. Nuber, U. & Scheffner, M. Identification of determinants in E2 ubiquitin-conjugating enzymes required for HECT E3 ubiquitin–protein ligase interaction. J. Biol. Chem. 274, 7576–7582 (1999).

    CAS  PubMed  Google Scholar 

  80. Ogunjimi, A. A. et al. Regulation of Smurf2 ubiquitin ligase activity by anchoring the E2 to the HECT domain. Mol. Cell 19, 297–308 (2005).

    CAS  PubMed  Google Scholar 

  81. Maspero, E. et al. Structure of a ubiquitin-loaded HECT ligase reveals the molecular basis for catalytic priming. Nat. Struct. Mol. Biol. 20, 696–701 (2013). The first crystal structure of a primed HECT E3ubiquitin complex.

    CAS  PubMed  Google Scholar 

  82. Kamadurai, H. B. et al. Mechanism of ubiquitin ligation and lysine prioritization by a HECT E3. eLife 2, e00828 (2013). The first crystal structure of a HECT E3ubiquitin–substrate peptide complex.

    PubMed  PubMed Central  Google Scholar 

  83. Salvat, C., Wang, G., Dastur, A., Lyon, N. & Huibregtse, J. M. The -4 phenylalanine is required for substrate ubiquitination catalyzed by HECT ubiquitin ligases. J. Biol. Chem. 279, 18935–18943 (2004).

    CAS  PubMed  Google Scholar 

  84. Ronchi, V. P., Klein, J. M. & Haas, A. L. E6AP/UBE3A ubiquitin ligase harbors two E2ubiquitin binding sites. J. Biol. Chem. 288, 10349–10360 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  85. French, M. E., Kretzmann, B. R. & Hicke, L. Regulation of the RSP5 ubiquitin ligase by an intrinsic ubiquitin-binding site. J. Biol. Chem. 284, 12071–12079 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  86. Maspero, E. et al. Structure of the HECT:ubiquitin complex and its role in ubiquitin chain elongation. EMBO Rep. 12, 342–349 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  87. Kim, H. C., Steffen, A. M., Oldham, M. L., Chen, J. & Huibregtse, J. M. Structure and function of a HECT domain ubiquitin-binding site. EMBO Rep. 12, 334–341 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  88. Stieglitz, B. et al. Structural basis for ligase-specific conjugation of linear ubiquitin chains by HOIP. Nature 503, 422–426 (2013). The first crystal structure of a RBR RING2 bound to donor and acceptor ubiquitin.

    CAS  PubMed  PubMed Central  Google Scholar 

  89. Spratt, D. E. et al. A molecular explanation for the recessive nature of parkin-linked Parkinson's disease. Nat. Commun. 4, 1983 (2013).

    PubMed  Google Scholar 

  90. Beasley, S. A., Hristova, V. A. & Shaw, G. S. Structure of the Parkin in-between-ring domain provides insights for E3-ligase dysfunction in autosomal recessive Parkinson's disease. Proc. Natl Acad. Sci. USA 104, 3095–3100 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  91. Spratt, D. E., Mercier, P. & Shaw, G. S. Structure of the HHARI catalytic domain shows glimpses of a HECT E3 ligase. PLoS ONE 8, e74047 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  92. Lechtenberg, B. C. et al. Structure of a HOIP/E2ubiquitin complex reveals RBR E3 ligase mechanism and regulation. Nature 529, 546–550 (2016). The first crystal structure of a RBR domain bound to E2ubiquitin.

    CAS  PubMed  PubMed Central  Google Scholar 

  93. Duda, D. M. et al. Structure of HHARI, a RING-IBR-RING ubiquitin ligase: autoinhibition of an Ariadne-family E3 and insights into ligation mechanism. Structure 21, 1030–1041 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  94. Riley, B. E. et al. Structure and function of Parkin E3 ubiquitin ligase reveals aspects of RING and HECT ligases. Nat. Commun. 4, 1982 (2013).

    CAS  PubMed  Google Scholar 

  95. Wauer, T. & Komander, D. Structure of the human Parkin ligase domain in an autoinhibited state. EMBO J. 32, 2099–2112 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  96. Trempe, J. F. et al. Structure of parkin reveals mechanisms for ubiquitin ligase activation. Science 340, 1451–1455 (2013). The first crystal structure of full-length PARKIN in an autoinhibited conformation.

    CAS  PubMed  Google Scholar 

  97. Kumar, A. et al. Disruption of the autoinhibited state primes the E3 ligase parkin for activation and catalysis. EMBO J. 34, 2506–2521 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  98. Stieglitz, B., Morris-Davies, A. C., Koliopoulos, M. G., Christodoulou, E. & Rittinger, K. LUBAC synthesizes linear ubiquitin chains via a thioester intermediate. EMBO Rep. 13, 840–846 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  99. Smit, J. J. et al. The E3 ligase HOIP specifies linear ubiquitin chain assembly through its RING-IBR-RING domain and the unique LDD extension. EMBO J. 31, 3833–3844 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  100. Christensen, D. E., Brzovic, P. S. & Klevit, R. E. E2–BRCA1 RING interactions dictate synthesis of mono- or specific polyubiquitin chain linkages. Nat. Struct. Mol. Biol. 14, 941–948 (2007).

    CAS  PubMed  Google Scholar 

  101. Rodrigo-Brenni, M. C. & Morgan, D. O. Sequential E2s drive polyubiquitin chain assembly on APC targets. Cell 130, 127–139 (2007).

    CAS  PubMed  Google Scholar 

  102. Jin, L., Williamson, A., Banerjee, S., Philipp, I. & Rape, M. Mechanism of ubiquitin-chain formation by the human anaphase-promoting complex. Cell 133, 653–665 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  103. McGinty, R. K., Henrici, R. C. & Tan, S. Crystal structure of the PRC1 ubiquitylation module bound to the nucleosome. Nature 514, 591–596 (2014). Reports a crystal structure showing how RNF2-BMI1 monoubiquitylates histone.

    CAS  PubMed  PubMed Central  Google Scholar 

  104. Chang, L., Zhang, Z., Yang, J., McLaughlin, S. H. & Barford, D. Atomic structure of the APC/C and its mechanism of protein ubiquitination. Nature 522, 450–454 (2015). The first atomic structure of APC/C, revealing the mechanism of ubiquitylation.

    CAS  PubMed  PubMed Central  Google Scholar 

  105. Brown, N. G. et al. RING E3 mechanism for ubiquitin ligation to a disordered substrate visualized for human anaphase-promoting complex. Proc. Natl Acad. Sci. USA 112, 5272–5279 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  106. McNatt, M. W., McKittrick, I., West, M. & Odorizzi, G. Direct binding to Rsp5 mediates ubiquitin-independent sorting of Sna3 via the multivesicular body pathway. Mol. Biol. Cell 18, 697–706 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  107. Oestreich, A. J. et al. Characterization of multiple multivesicular body sorting determinants within Sna3: a role for the ubiquitin ligase Rsp5. Mol. Biol. Cell 18, 707–720 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  108. Stawiecka-Mirota, M. et al. Targeting of Sna3p to the endosomal pathway depends on its interaction with Rsp5p and multivesicular body sorting on its ubiquitylation. Traffic 8, 1280–1296 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  109. Watson, H. & Bonifacino, J. S. Direct binding to Rsp5p regulates ubiquitination-independent vacuolar transport of Sna3p. Mol. Biol. Cell 18, 1781–1789 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  110. Wang, H. et al. Role of histone H2A ubiquitination in Polycomb silencing. Nature 431, 873–878 (2004).

    CAS  PubMed  Google Scholar 

  111. Dou, H. et al. Structural basis for autoinhibition and phosphorylation-dependent activation of c-Cbl. Nat. Struct. Mol. Biol. 19, 184–192 (2012).

    CAS  PubMed  Google Scholar 

  112. Kobashigawa, Y. et al. Autoinhibition and phosphorylation-induced activation mechanisms of human cancer and autoimmune disease-related E3 protein Cbl-b. Proc. Natl Acad. Sci. USA 108, 20579–20584 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  113. Duda, D. M. et al. Structural insights into NEDD8 activation of cullin-RING ligases: conformational control of conjugation. Cell 134, 995–1006 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  114. Calabrese, M. F. et al. A RING E3-substrate complex poised for ubiquitin-like protein transfer: structural insights into cullin-RING ligases. Nat. Struct. Mol. Biol. 18, 947–949 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  115. Zheng, N. et al. Structure of the Cul1–Rbx1–Skp1–F boxSkp2 SCF ubiquitin ligase complex. Nature 416, 703–709 (2002).

    CAS  PubMed  Google Scholar 

  116. Chang, L., Zhang, Z., Yang, J., McLaughlin, S. H. & Barford, D. Molecular architecture and mechanism of the anaphase-promoting complex. Nature 513, 388–393 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  117. Merbl, Y. & Kirschner, M. W. Large-scale detection of ubiquitination substrates using cell extracts and protein microarrays. Proc. Natl Acad. Sci. USA 106, 2543–2548 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  118. Ordureau, A. et al. Quantitative proteomics reveal a feedforward mechanism for mitochondrial PARKIN translocation and ubiquitin chain synthesis. Mol. Cell 56, 360–375 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  119. Eddins, M. J., Carlile, C. M., Gomez, K. M., Pickart, C. M. & Wolberger, C. Mms2–Ubc13 covalently bound to ubiquitin reveals the structural basis of linkage-specific polyubiquitin chain formation. Nat. Struct. Mol. Biol. 13, 915–920 (2006).

    CAS  PubMed  Google Scholar 

  120. Brown, N. G. et al. Mechanism of polyubiquitination by human anaphase-promoting complex: RING repurposing for ubiquitin chain assembly. Mol. Cell 56, 246–260 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  121. Kelly, A., Wickliffe, K. E., Song, L., Fedrigo, I. & Rape, M. Ubiquitin chain elongation requires E3-dependent tracking of the emerging conjugate. Mol. Cell 56, 232–245 (2014).

    CAS  PubMed  Google Scholar 

  122. Peters, J. M. The anaphase promoting complex/cyclosome: a machine designed to destroy. Nat. Rev. Mol. Cell Biol. 7, 644–656 (2006).

    CAS  PubMed  Google Scholar 

  123. Frye, J. J. et al. Electron microscopy structure of human APC/CCDH1–EMI1 reveals multimodal mechanism of E3 ligase shutdown. Nat. Struct. Mol. Biol. 20, 827–835 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  124. Wang, W. & Kirschner, M. W. Emi1 preferentially inhibits ubiquitin chain elongation by the anaphase-promoting complex. Nat. Cell Biol. 15, 797–806 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  125. Fulda, S. & Vucic, D. Targeting IAP proteins for therapeutic intervention in cancer. Nat. Rev. Drug Discov. 11, 109–124 (2012).

    CAS  PubMed  Google Scholar 

  126. Dueber, E. C. et al. Antagonists induce a conformational change in cIAP1 that promotes autoubiquitination. Science 334, 376–380 (2011).

    CAS  PubMed  Google Scholar 

  127. Lopez, J. et al. CARD-mediated autoinhibition of cIAP1's E3 ligase activity suppresses cell proliferation and migration. Mol. Cell 42, 569–583 (2011).

    CAS  PubMed  Google Scholar 

  128. Phillips, A. H. et al. Internal motions prime cIAP1 for rapid activation. Nat. Struct. Mol. Biol. 21, 1068–1074 (2014).

    CAS  PubMed  Google Scholar 

  129. Feltham, R. et al. Smac mimetics activate the E3 ligase activity of cIAP1 protein by promoting RING domain dimerization. J. Biol. Chem. 286, 17015–17028 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  130. Mund, T. & Pelham, H. R. Control of the activity of WW-HECT domain E3 ubiquitin ligases by NDFIP proteins. EMBO Rep. 10, 501–507 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  131. Riling, C. et al. Itch WW domains inhibit its E3 ubiquitin ligase activity by blocking E2-E3 ligase trans-thiolation. J. Biol. Chem. 290, 23875–23887 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  132. Gallagher, E., Gao, M., Liu, Y. C. & Karin, M. Activation of the E3 ubiquitin ligase Itch through a phosphorylation-induced conformational change. Proc. Natl Acad. Sci. USA 103, 1717–1722 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  133. Wan, L. et al. Cdh1 regulates osteoblast function through an APC/C-independent modulation of Smurf1. Mol. Cell 44, 721–733 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  134. Wang, J. et al. Calcium activates Nedd4 E3 ubiquitin ligases by releasing the C2 domain-mediated auto-inhibition. J. Biol. Chem. 285, 12279–12288 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  135. Wiesner, S. et al. Autoinhibition of the HECT-type ubiquitin ligase Smurf2 through its C2 domain. Cell 130, 651–662 (2007).

    CAS  PubMed  Google Scholar 

  136. Mari, S. et al. Structural and functional framework for the autoinhibition of Nedd4-family ubiquitin ligases. Structure 22, 1639–1649 (2014).

    CAS  PubMed  Google Scholar 

  137. Aragon, E. et al. Structural basis for the versatile interactions of Smad7 with regulator WW domains in TGF-β pathways. Structure 20, 1726–1736 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  138. Chaugule, V. K. et al. Autoregulation of Parkin activity through its ubiquitin-like domain. EMBO J. 30, 2853–2867 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  139. Narendra, D., Tanaka, A., Suen, D. F. & Youle, R. J. Parkin is recruited selectively to impaired mitochondria and promotes their autophagy. J. Cell Biol. 183, 795–803 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  140. Kondapalli, C. et al. PINK1 is activated by mitochondrial membrane potential depolarization and stimulates Parkin E3 ligase activity by phosphorylating Serine 65. Open Biol. 2, 120080 (2012).

    PubMed  PubMed Central  Google Scholar 

  141. Shiba-Fukushima, K. et al. PINK1-mediated phosphorylation of the Parkin ubiquitin-like domain primes mitochondrial translocation of Parkin and regulates mitophagy. Sci. Rep. 2, 1002 (2012).

    PubMed  PubMed Central  Google Scholar 

  142. Shiba-Fukushima, K., Inoshita, T., Hattori, N. & Imai, Y. PINK1-mediated phosphorylation of Parkin boosts Parkin activity in Drosophila. PLoS Genet. 10, e1004391 (2014).

    PubMed  PubMed Central  Google Scholar 

  143. Koyano, F. et al. Ubiquitin is phosphorylated by PINK1 to activate parkin. Nature 510, 162–166 (2014).

    CAS  PubMed  Google Scholar 

  144. Kane, L. A. et al. PINK1 phosphorylates ubiquitin to activate Parkin E3 ubiquitin ligase activity. J. Cell Biol. 205, 143–153 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  145. Kazlauskaite, A. et al. Parkin is activated by PINK1-dependent phosphorylation of ubiquitin at Ser65. Biochem. J. 460, 127–139 (2014).

    CAS  PubMed  Google Scholar 

  146. Ordureau, A. et al. Defining roles of PARKIN and ubiquitin phosphorylation by PINK1 in mitochondrial quality control using a ubiquitin replacement strategy. Proc. Natl Acad. Sci. USA 112, 6637–6642 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  147. Kazlauskaite, A. et al. Binding to serine 65-phosphorylated ubiquitin primes Parkin for optimal PINK1-dependent phosphorylation and activation. EMBO Rep. 16, 939–954 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  148. Sarraf, S. A. et al. Landscape of the PARKIN-dependent ubiquitylome in response to mitochondrial depolarization. Nature 496, 372–376 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  149. Bingol, B. et al. The mitochondrial deubiquitinase USP30 opposes parkin-mediated mitophagy. Nature 510, 370–375 (2014).

    CAS  PubMed  Google Scholar 

  150. Sauve, V. et al. A Ubl/ubiquitin switch in the activation of Parkin. EMBO J. 34, 2492–2505 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  151. Wauer, T., Simicek, M., Schubert, A. & Komander, D. Mechanism of phospho-ubiquitin-induced PARKIN activation. Nature 524, 370–374 (2015). Reports a crystal structure showing how phospho-ubiquitin activates PARKIN.

    CAS  PubMed  PubMed Central  Google Scholar 

  152. Kulathu, Y. & Komander, D. Atypical ubiquitylation — the unexplored world of polyubiquitin beyond Lys48 and Lys63 linkages. Nat. Rev. Mol. Cell Biol. 13, 508–523 (2012).

    CAS  PubMed  Google Scholar 

  153. Rosner, D., Schneider, T., Schneider, D., Scheffner, M. & Marx, A. Click chemistry for targeted protein ubiquitylation and ubiquitin chain formation. Nat. Protoc. 10, 1594–1611 (2015).

    PubMed  Google Scholar 

  154. Eger, S. et al. Generation of a mono-ubiquitinated PCNA mimic by click chemistry. Chembiochem 12, 2807–2812 (2011).

    CAS  PubMed  Google Scholar 

  155. McGinty, R. K., Kim, J., Chatterjee, C., Roeder, R. G. & Muir, T. W. Chemically ubiquitylated histone H2B stimulates hDot1L-mediated intranucleosomal methylation. Nature 453, 812–816 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  156. Chen, J., Ai, Y., Wang, J., Haracska, L. & Zhuang, Z. Chemically ubiquitylated PCNA as a probe for eukaryotic translesion DNA synthesis. Nat. Chem. Biol. 6, 270–272 (2010).

    CAS  PubMed  Google Scholar 

  157. Sommer, S., Weikart, N. D., Brockmeyer, A., Janning, P. & Mootz, H. D. Expanded click conjugation of recombinant proteins with ubiquitin-like modifiers reveals altered substrate preference of SUMO2-modified Ubc9. Angew. Chem. Int. Ed. Engl. 50, 9888–9892 (2011).

    CAS  PubMed  Google Scholar 

  158. Oualid, F. E., Hameed, D. S., Atmioui, D. E., Hilkmann, H. & Ovaa, H. Synthesis of atypical diubiquitin chains. Methods Mol. Biol. 832, 597–609 (2012).

    PubMed  Google Scholar 

  159. Popovic, D., Vucic, D. & Dikic, I. Ubiquitination in disease pathogenesis and treatment. Nat. Med. 20, 1242–1253 (2014).

    CAS  PubMed  Google Scholar 

  160. Husnjak, K. & Dikic, I. Ubiquitin-binding proteins: decoders of ubiquitin-mediated cellular functions. Annu. Rev. Biochem. 81, 291–322 (2012).

    CAS  PubMed  Google Scholar 

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Acknowledgements

The author's research was supported by Cancer Research UK and the European Research Council (grant number 647849).

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DATABASES

RCSB Protein Data Bank

Glossary

Isopeptide bond

An amide bond formed between the amino group of a lysine side chain on a protein (substrate) and the carboxyl terminus of another protein (ubiquitin).

ε-amino group

Refers to the NH3+ group in a lysine side chain. This group has a high acid dissociation constant (pKa), and often the active site environment (or environments) of ubiquitin-activating and ubiquitin-conjugating enzymes or substrates can assist in lowering the pKa of this NH3+ group to increase its reactivity.

26S proteasome

A large protein complex that degrades proteins modified with ubiquitin chains. The 26S proteasome contains a 20S core particle that accommodates the protease catalytic subunits and two 19S regulatory subunits that recognize ubiquitylated substrates and facilitate substrate unfolding before entry into the 20S core particle.

NF-κB pathway

A signalling pathway that activates the transcription factor nuclear factor-κB (NF-κB) in response to stimuli such as pro-inflammatory cytokines, bacterial and viral infections, and antigen receptor binding. Activated NF-κB leads to the expression of genes that are regulators of apoptosis, cell survival, proliferation and immunity.

Pyrimidine dimer photolesions

Ultraviolet radiation-induced dimer formation between two consecutive pyrimidine bases on one strand of DNA. This process breaks the normal base pairing in double-stranded DNA.

Nucleotide excision repair

A DNA repair mechanism that removes a short damaged single-stranded DNA induced by ultraviolet radiation. The undamaged single-stranded DNA is used as a template to synthesize a short complementary sequence for ligation.

Anaphase promoting complex/cyclosome

(APC/C). A multi-subunit RING (really interesting new gene) ubiquitin ligase complex that has a central role in cell cycle progression by ubiquitylating cell cycle proteins and targeting them for degradation.

PY motifs

Short proline-rich motifs containing a proline-proline-x-tyrosine (x is any amino acid) sequence that is recognized by a WW domain.

Allosteric changes

Refer to changes induced in one part of a molecule, usually an active site of an enzyme, by a distal binding event.

Nuclear magnetic resonance

(NMR). A technique that provides detailed information about protein structure and dynamics in solution by probing the magnetic properties of certain atomic nuclei. The magnetic properties of atoms change when their chemical environments are altered (for example, protein–protein interactions).

Small-angle X-ray scattering

(SAXS). A technique whereby the elastic scattering of X-rays by a protein in solution is used to provide information about the protein's shape and size.

SUMO

A ubiquitin-like protein modifier that has its own dedicated ubiquitin-activating enzyme (E1)- ubiquitin-conjugating enzyme (E2)-ubiquitin ligase (E3) cascade for modification of protein substrates.

Acid dissociation constant

(pKa). A measure of the strength of an acid in solution, indicating the protonation state of an amino acid in solution. Reducing the pKa facilitates deprotonation.

Multivesicular body

A type of late endosome that contains membrane-bound vesicles within its lumen. Fusion with lysosomes leads to degradation of its contents, whereas fusion with the plasma membrane releases its contents into the extracellular space.

Crystallographic symmetry

Crystals are formed from repeating subunits in which the minimal subunit is referred to as the asymmetric unit. Crystallographic symmetry refers to how these asymmetric units pack to form a crystal.

Polycomb-group proteins

A family of proteins that have important roles in cellular differentiation and development by remodelling chromatin to repress transcription. They form part of the multiprotein complexes called Polycomb repressive complexes.

Nucleosome core particle

(NCP). A basic repeating unit of DNA packaging found in eukaryotes. A single NCP contains 147 base pairs of DNA wrapped around a histone octamer consisting of two histone H2A-H2B dimers and a histone H3-H4 tetramer.

Mitophagy

Degradation of damaged mitochondria by autophagy, during which mitochondria are decorated with polyubiquitin chains, engulfed by autophagosomes and degraded following lysosomal fusion.

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Buetow, L., Huang, D. Structural insights into the catalysis and regulation of E3 ubiquitin ligases. Nat Rev Mol Cell Biol 17, 626–642 (2016). https://doi.org/10.1038/nrm.2016.91

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