Review Article | Published:

Translation inhibition and stress granules in the antiviral immune response

Nature Reviews Immunology volume 17, pages 647660 (2017) | Download Citation

Abstract

Efficient viral gene expression is threatened by cellular stress response programmes that rapidly reprioritize the translation machinery in response to varied environmental assaults, including virus infection. This results in inhibition of bulk synthesis of housekeeping proteins and causes the aggregation of messenger ribonucleoprotein complexes into cytoplasmic foci that are known as stress granules, which can entrap viral mRNAs. There is accumulating evidence for the antiviral nature of stress granules, which is supported by the discovery of many viral factors that interfere with stress granule formation and/or function. This Review focuses on recent advances in our understanding of the role of translation inhibition and stress granules in antiviral immune responses.

Key points

  • Stress granules form when cells sense stress and rapidly arrest protein synthesis. Double-stranded RNA-activated protein kinase (PKR) is the main sensor protein that detects virus infection and phosphorylates eukaryotic translation initiation factor 2α (eIF2α) to stall bulk protein synthesis and elicit the formation of stress granules.

  • Many viruses have evolved diverse mechanisms to prevent the formation of stress granules and enable the synthesis of viral proteins using the host translation machinery.

  • Stress granules facilitate the establishment of an antiviral state by limiting viral protein accumulation and regulating signalling cascades that affect virus replication and immune responses.

  • Mechanisms have been described that enable the ongoing translation of messenger ribonucleoproteins (mRNPs) that encode antiviral factors such as interferon-stimulated genes (ISGs) despite the arrest of bulk translation.

  • Further elucidation of the role of stress granules in antiviral defence will probably depend on recent technical advances in translatome analysis and super-resolution microscopy, which have revolutionized our ability to study the composition and properties of stress granules.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    & RNA granules: post-transcriptional and epigenetic modulators of gene expression. Nat. Rev. Mol. Cell Biol. 10, 430–436 (2009).

  2. 2.

    & Stress granules: the Tao of RNA triage. Trends Biochem. Sci. 33, 141–150 (2008).

  3. 3.

    , & Stress granules and cell signaling: more than just a passing phase? Trends Biochem. Sci. 38, 494–506 (2013).

  4. 4.

    , , , & Importance of eIF2α phosphorylation and stress granule assembly in alphavirus translation regulation. Mol. Biol. Cell 16, 3753–3763 (2005).

  5. 5.

    et al. Critical role of an antiviral stress granule containing RIG-I and PKR in viral detection and innate immunity. PLoS ONE 7, e43031 (2012).

  6. 6.

    , & The mechanism of eukaryotic translation initiation and principles of its regulation. Nat. Rev. Mol. Cell Biol. 11, 113–127 (2010).

  7. 7.

    & Principles and properties of stress granules. Trends Cell Biol. 26, 668–679 (2016).

  8. 8.

    & Regulation of stress granules in virus systems. Trends Microbiol. 20, 175–183 (2012).

  9. 9.

    , , , & Who regulates whom? An overview of RNA granules and viral infections. Viruses 8, E180 (2016).

  10. 10.

    , & mTOR: from growth signal integration to cancer, diabetes and ageing. Nat. Rev. Mol. Cell Biol. 12, 21–35 (2011).

  11. 11.

    , , & The mRNA cap-binding protein eIF4E in post-transcriptional gene expression. Nat. Struct. Mol. Biol. 11, 503–511 (2004).

  12. 12.

    et al. Heme-regulated inhibitor kinase-mediated phosphorylation of eukaryotic translation initiation factor 2 inhibits translation, induces stress granule formation, and mediates survival upon arsenite exposure. J. Biol. Chem. 280, 16925–16933 (2005).

  13. 13.

    , & Translation initiation control by heme-regulated eukaryotic initiation factor 2α kinase in erythroid cells under cytoplasmic stresses. Mol. Cell. Biol. 21, 7971–7980 (2001).

  14. 14.

    , & The histidyl-tRNA synthetase-related sequence in the eIF-2α protein kinase GCN2 interacts with tRNA and is required for activation in response to starvation for different amino acids. Mol. Cell. Biol. 15, 4497–4506 (1995).

  15. 15.

    et al. Activation of GCN2 in UV-irradiated cells inhibits translation. Curr. Biol. 12, 1279–1286 (2002).

  16. 16.

    , & The dsRNA protein kinase PKR: virus and cell control. Biochimie 89, 799–811 (2007).

  17. 17.

    , , , & Perk is essential for translational regulation and cell survival during the unfolded protein response. Mol. Cell 5, 897–904 (2000).

  18. 18.

    Translational control during heat shock. Biochimie 76, 737–747 (1994).

  19. 19.

    , , & RNA granules: the good, the bad and the ugly. Cell. Signal. 23, 324–334 (2011).

  20. 20.

    & Reinitiation involving upstream ORFs regulates ATF4 mRNA translation in mammalian cells. Proc. Natl Acad. Sci. USA 101, 11269–11274 (2004).

  21. 21.

    et al. Stress-induced gene expression requires programmed recovery from translational repression. EMBO J. 22, 1180–1187 (2003).

  22. 22.

    et al. Inhibition of eukaryotic translation initiation by the marine natural product pateamine A. Mol. Cell 20, 709–722 (2005).

  23. 23.

    et al. Inhibition of ribosome recruitment induces stress granule formation independently of eukaryotic initiation factor α phosphorylation. Mol. Biol. Cell 17, 4212–4219 (2006).

  24. 24.

    et al. Ribosomal protein S6 is highly expressed in non-Hodgkin lymphoma and associates with mRNA containing a 5′ terminal oligopyrimidine tract. Oncogene 30, 1531–1541 (2011).

  25. 25.

    , & Selenite targets eIF4E-binding protein-1 to inhibit translation initiation and induce the assembly of non-canonical stress granules. Nucleic Acids Res. 40, 8099–8110 (2012).

  26. 26.

    et al. Hydrogen peroxide induces stress granule formation independent of eIF2α phosphorylation. Biochem. Biophys. Res. Commun. 423, 763–769 (2012).

  27. 27.

    , , , & A functional RNAi screen links O-GlcNAc modification of ribosomal proteins to stress granule and processing body assembly. Nat. Cell Biol. 10, 1224–1231 (2008).

  28. 28.

    et al. Dynamic shuttling of TIA-1 accompanies the recruitment of mRNA to mammalian stress granules. J. Cell Biol. 151, 1257–1268 (2000).

  29. 29.

    , & Disruption of microtubules inhibits cytoplasmic ribonucleoprotein stress granule formation. Exp. Cell Res. 290, 227–233 (2003).

  30. 30.

    , , & Dynein and kinesin regulate stress-granule and P-body dynamics. J. Cell Sci. 122, 3973–3982 (2009).

  31. 31.

    & Visibly stressed: the role of eIF2, TIA-1, and stress granules in protein translation. Cell Stress Chaperones 7, 213–221 (2002).

  32. 32.

    , , , & RNA-binding proteins TIA-1 and TIAR link the phosphorylation of eIF-2α to the assembly of mammalian stress granules. J. Cell Biol. 147, 1431–1441 (1999).

  33. 33.

    et al. The RasGAP-associated endoribonuclease G3BP assembles stress granules. J. Cell Biol. 160, 823–831 (2003).

  34. 34.

    & Mammalian stress granules and processing bodies. Methods Enzymol. 431, 61–81 (2007). This paper provides excellent protocols for the induction and immunofluorescent detection of stress granules, as well as information about commercially available antibodies for common stress granule markers.

  35. 35.

    et al. Stress granule assembly is mediated by prion-like aggregation of TIA-1. Mol. Biol. Cell 15, 5383–5398 (2004).

  36. 36.

    et al. Both G3BP1 and G3BP2 contribute to stress granule formation. Genes Cells 18, 135–146 (2013).

  37. 37.

    et al. Stress granules and processing bodies are dynamically linked sites of mRNP remodeling. J. Cell Biol. 169, 871–884 (2005).

  38. 38.

    Distinct stages in stress granule assembly and disassembly. eLife 5, e18413 (2016).

  39. 39.

    , , & Formation and maturation of phase-separated liquid droplets by RNA-binding proteins. Mol. Cell 60, 208–219 (2015).

  40. 40.

    , & The deacetylase HDAC6 is a novel critical component of stress granules involved in the stress response. Genes Dev. 21, 3381–3394 (2007).

  41. 41.

    et al. Poly(ADP-ribose) regulates stress responses and microRNA activity in the cytoplasm. Mol. Cell 42, 489–499 (2011).

  42. 42.

    et al. Arginine demethylation of G3BP1 promotes stress granule assembly. J. Biol. Chem. 291, 22671–22685 (2016).

  43. 43.

    et al. NEDDylation promotes stress granule assembly. Nat. Commun. 7, 12125 (2016).

  44. 44.

    , & Protein kinase R is responsible for the phosphorylation of eIF2α in rotavirus infection. J. Virol. 84, 10457–10466 (2010).

  45. 45.

    , & Viral double-stranded RNAs from vaccinia virus early or intermediate gene transcripts possess PKR activating function, resulting in NF-κB activation, when the K1 protein is absent or mutated. J. Biol. Chem. 286, 7765–7778 (2011).

  46. 46.

    et al. RNA dimerization promotes PKR dimerization and activation. J. Mol. Biol. 390, 319–338 (2009).

  47. 47.

    et al. 5′-triphosphate-dependent activation of PKR by RNAs with short stem–loops. Science 318, 1455–1458 (2007).

  48. 48.

    , & Regulation of innate immunity through RNA structure and the protein kinase PKR. Curr. Opin. Struct. Biol. 21, 119–127 (2011).

  49. 49.

    et al. Influenza B virus ribonucleoprotein is a potent activator of the antiviral kinase PKR. PLoS Pathog. 5, e1000473 (2009).

  50. 50.

    et al. Antiviral effect of the mammalian translation initiation factor 2α kinase GCN2 against RNA viruses. EMBO J. 25, 1730–1740 (2006).

  51. 51.

    & Hepatitis C virus envelope proteins regulate CHOP via induction of the unfolded protein response. FASEB J. 19, 1510–1512 (2005).

  52. 52.

    , & Herpes simplex virus 1 infection activates the endoplasmic reticulum resident kinase PERK and mediates eIF-2 dephosphorylation by the 134.5 protein. J. Virol. 79, 1379–1388 (2005).

  53. 53.

    & Host translation at the nexus of infection and immunity. Cell Host Microbe 12, 470–483 (2012).

  54. 54.

    , & Cap-to-tail guide to mRNA translation strategies in virus-infected cells. Annu. Rev. Virol. 3, 283–307 (2016).

  55. 55.

    , & Influenza A virus inhibits cytoplasmic stress granule formation. FASEB J. 26, 1629–1639 (2012).

  56. 56.

    , , & Inhibition of cytoplasmic mRNA stress granule formation by a viral proteinase. Cell Host Microbe 2, 295–305 (2007). This is the first study to describe direct interference with stress granule formation by proteolytic cleavage of G3BP1 and show the antiviral effect of stress granule formation.

  57. 57.

    et al. Dynamic oscillation of translation and stress granule formation mark the cellular response to virus infection. Cell Host Microbe 12, 71–85 (2012). This is the first study to describe the dynamic oscillation of translation arrest and recovery as a feature of intrinsic immune responses to virus infection.

  58. 58.

    et al. Influenza A virus host shutoff disables antiviral stress-induced translation arrest. PLoS Pathog. 10, e1004217 (2014).

  59. 59.

    & The leader protein of cardioviruses inhibits stress granule assembly. J. Virol. 85, 9614–9622 (2011).

  60. 60.

    , , , & Herpes simplex virus 2 virion host shutoff endoribonuclease activity is required to disrupt stress granule formation. J. Virol. 90, 7943–7955 (2016).

  61. 61.

    , & Pattern recognition and signaling mechanisms of RIG-I and MDA5. Front. Immunol. 5, 342 (2014).

  62. 62.

    et al. Reconstitution of the RIG-I pathway reveals a signaling role of unanchored polyubiquitin chains in innate immunity. Cell 141, 315–330 (2010).

  63. 63.

    & How RIG-I like receptors activate MAVS. Curr. Opin. Virol. 12, 91–98 (2015).

  64. 64.

    & MAVS coordination of antiviral innate immunity. J. Virol. 89, 6974–6977 (2015).

  65. 65.

    et al. Induction of GADD34 is necessary for dsRNA-dependent interferon-β production and participates in the control of Chikungunya virus infection. PLoS Pathog. 8, e1002708 (2012).

  66. 66.

    et al. Stress granules regulate double-stranded RNA-dependent protein kinase activation through a complex containing G3BP1 and caprin1. mBio 6, e02486 (2015).

  67. 67.

    , & MDA5 localizes to stress granules, but this localization is not required for the induction of type I interferon. J. Virol. 87, 6314–6325 (2013).

  68. 68.

    , , , & Subcellular localizations of RIG-I, TRIM25 and MAVS complexes. J. Virol. 91, e01155–16 (2017).

  69. 69.

    , , , & Sequestration of TRAF2 into stress granules interrupts tumor necrosis factor signaling under stress conditions. Mol. Cell. Biol. 25, 2450–2462 (2005).

  70. 70.

    et al. DHX36 enhances RIG-I signaling by facilitating PKR-mediated antiviral stress granule formation. PLoS Pathog. 10, e1004012 (2014).

  71. 71.

    et al. Aspartate-glutamate-alanine-histidine box motif (DEAH)/RNA helicase A helicases sense microbial DNA in human plasmacytoid dendritic cells. Proc. Natl Acad. Sci. USA 107, 15181–15186 (2010).

  72. 72.

    et al. DDX1, DDX21, and DHX36 helicases form a complex with the adaptor molecule TRIF to sense dsRNA in dendritic cells. Immunity 34, 866–878 (2011).

  73. 73.

    et al. TRIM25 RING-finger E3 ubiquitin ligase is essential for RIG-I-mediated antiviral activity. Nature 446, 916–920 (2007).

  74. 74.

    & The stress granule protein G3BP1 recruits protein kinase R to promote multiple innate immune antiviral responses. J. Virol. 89, 2575–2589 (2015). This study shows the positive feedback loop of PKR activation through its recruitment to stress granules by G3BP1.

  75. 75.

    et al. Protein kinase R contributes to immunity against specific viruses by regulating interferon mRNA integrity. Cell Host Microbe 7, 354–361 (2010).

  76. 76.

    & Protein kinase PKR catalytic activity is required for the PKR-dependent activation of mitogen-activated protein kinases and amplification of interferon β induction following virus infection. Virology 427, 208–216 (2012).

  77. 77.

    , , & Activation of the interferon induction cascade by influenza A viruses requires viral RNA synthesis and nuclear export. J. Virol. 88, 3942–3952 (2014).

  78. 78.

    et al. Differential roles of MDA5 and RIG-I helicases in the recognition of RNA viruses. Nature 441, 101–105 (2006).

  79. 79.

    , , , & Systematic identification of type I and type II interferon-induced antiviral factors. Proc. Natl Acad. Sci. USA 109, 4239–4244 (2012).

  80. 80.

    et al. Activation of the p70 S6 kinase and phosphorylation of the 4E-BP1 repressor of mRNA translation by type I interferons. J. Biol. Chem. 278, 27772–27780 (2003).

  81. 81.

    et al. Regulatory effects of mammalian target of rapamycin-activated pathways in type I and II interferon signaling. J. Biol. Chem. 282, 1757–1768 (2007).

  82. 82.

    et al. Protein phosphatase 1 subunit Ppp1r15a/GADD34 regulates cytokine production in polyinosinic:polycytidylic acid-stimulated dendritic cells. Proc. Natl Acad. Sci. USA 109, 3006–3011 (2012).

  83. 83.

    et al. Protein synthesis inhibition and GADD34 control IFN-β heterogeneous expression in response to dsRNA. EMBO J. 36, e201695000 (2017). This study thoroughly examines the translation arrest and antiviral cytokine synthesis that occur concomitantly in poly(I:C)-treated cells. It shows a novel mechanism of GADD34 induction via IRF3 activation and proposes a model for cycles of consecutive translation arrest and recovery.

  84. 84.

    et al. The function of GADD34 is a recovery from a shutoff of protein synthesis induced by ER stress: elucidation by GADD34-deficient mice. FASEB J. 17, 1573–1575 (2003).

  85. 85.

    & The broad-spectrum antiviral functions of IFIT and IFITM proteins. Nat. Rev. Immunol. 13, 46–57 (2012).

  86. 86.

    Viral encounters with 2′,5′-oligoadenylate synthetase and RNase L during the interferon antiviral response. J. Virol. 81, 12720–12729 (2007).

  87. 87.

    Type I interferons in viral control and immune regulation. Curr. Opin. Virol. 16, 31–40 (2016).

  88. 88.

    , , & Editing of cellular self-RNAs by adenosine deaminase ADAR1 suppresses innate immune stress responses. J. Biol. Chem. 291, 6158–6168 (2016).

  89. 89.

    , , , & The oligoadenylate synthetase family: an ancient protein family with multiple antiviral activities. J. Interferon Cytokine Res. 31, 41–47 (2011).

  90. 90.

    et al. Antiviral activity of human OASL protein is mediated by enhancing signaling of the RIG-I RNA sensor. Immunity 40, 936–948 (2014).

  91. 91.

    et al. PARP12, an interferon-stimulated gene involved in the control of protein translation and inflammation. J. Biol. Chem. 289, 26642–26657 (2014).

  92. 92.

    et al. Zinc-finger antiviral protein mediates retinoic acid inducible gene I-like receptor-independent antiviral response to murine leukemia virus. Proc. Natl Acad. Sci. USA 110, 12379–12384 (2013).

  93. 93.

    et al. Structural basis for lack of ADP-ribosyltransferase activity in poly(ADP-ribose) polymerase-13/zinc finger antiviral protein. J. Biol. Chem. 290, 7336–7344 (2015).

  94. 94.

    et al. Proteome-wide identification of poly(ADP-ribose) binding proteins and poly(ADP-ribose)-associated protein complexes. Nucleic Acids Res. 36, 6959–6976 (2008).

  95. 95.

    , , & Quantitative proteomics and dynamic imaging reveal that G3BP-mediated stress granule assembly is poly(ADP-ribose)-dependent following exposure to MNNG-induced DNA alkylation. J. Cell Sci. 125, 4555–4566 (2012).

  96. 96.

    et al. DDX3 interacts with influenza A virus NS1 and NP proteins and exerts antiviral function through regulation of stress granule formation. J. Virol. 90, 3661–3675 (2016).

  97. 97.

    et al. NF90 is a novel influenza A virus NS1-interacting protein that antagonizes the inhibitory role of NS1 on PKR phosphorylation. FEBS Lett. 590, 2797–2810 (2016).

  98. 98.

    et al. NF90 exerts antiviral activity through regulation of PKR phosphorylation and stress granules in infected cells. J. Immunol. 192, 3753–3764 (2014).

  99. 99.

    et al. Nuclear factor 90 negatively regulates influenza virus replication by interacting with viral nucleoprotein. J. Virol. 83, 7850–7861 (2009).

  100. 100.

    et al. Stress granule components G3BP1 and G3BP2 play a proviral role early in Chikungunya virus replication. J. Virol. 89, 4457–4469 (2015).

  101. 101.

    et al. Ebola virus does not induce stress granule formation during infection and sequesters stress granule proteins within viral inclusions. J. Virol. 90, 7268–7284 (2016).

  102. 102.

    et al. Formation of antiviral cytoplasmic granules during orthopoxvirus infection. J. Virol. 85, 1581–1593 (2011). This study describes the unique antiviral granules that form in vaccinia virus-infected cells; these granules share components of stress granules but differ in terms of their composition and properties.

  103. 103.

    , , & The stress granule component TIA-1 binds tick-borne encephalitis virus RNA and is recruited to perinuclear sites of viral replication to inhibit viral translation. J. Virol. 88, 6611–6622 (2014).

  104. 104.

    & Hepatitis C virus blocks interferon effector function by inducing protein kinase R phosphorylation. Cell Host Microbe 6, 513–522 (2009).

  105. 105.

    , , , & Respiratory syncytial virus induces host RNA stress granules to facilitate viral replication. J. Virol. 84, 12274–12284 (2010).

  106. 106.

    & Internal initiation of translation of eukaryotic mRNA directed by a sequence derived from poliovirus RNA. Nature 334, 320–325 (1988).

  107. 107.

    et al. Caliciviruses differ in their functional requirements for eIF4F components. J. Biol. Chem. 281, 25315–25325 (2006).

  108. 108.

    , , & The eIF4AIII RNA helicase is a critical determinant of human cytomegalovirus replication. Virology 489, 194–201 (2016).

  109. 109.

    et al. The natural compound silvestrol is a potent inhibitor of Ebola virus replication. Antiviral Res. 137, 76–81 (2017).

  110. 110.

    , , & Adapting the stress response: viral subversion of the mTOR signaling pathway. Viruses 8, E152 (2016).

  111. 111.

    Akt/TSC/mTOR activation by the KSHV G protein-coupled receptor: emerging insights into the molecular oncogenesis and treatment of Kaposi's sarcoma. Cell Cycle 6, 438–443 (2007).

  112. 112.

    & Epstein–Barr virus, rapamycin, and host immune responses. Curr. Opin. Organ Transplant. 13, 563–568 (2008).

  113. 113.

    , & Immunoregulatory functions of mTOR inhibition. Nat. Rev. Immunol. 9, 324–337 (2009).

  114. 114.

    et al. The kinase mTOR modulates the antibody response to provide cross-protective immunity to lethal infection with influenza virus. Nat. Immunol. 14, 1266–1276 (2013).

  115. 115.

    et al. G3BP–caprin1–USP10 complexes mediate stress granule condensation and associate with 40S subunits. J. Cell Biol. 212, 845–860 (2016).

  116. 116.

    & Translational control in stress and apoptosis. Nat. Rev. Mol. Cell Biol. 6, 318–327 (2005).

  117. 117.

    et al. mRNA helicases: the tacticians of translational control. Nat. Rev. Mol. Cell Biol. 12, 235–245 (2011).

  118. 118.

    , , & Activation of stress response pathways promotes formation of antiviral granules and restricts virus replication. Mol. Cell. Biol. 34, 2003–2016 (2014).

  119. 119.

    et al. Dengue virus infection induces formation of G3BP1 granules in human lung epithelial cells. Arch. Virol. 160, 2991–2999 (2015).

  120. 120.

    et al. The translation inhibitor silvestrol exhibits direct anti-tumor activity while preserving innate and adaptive immunity against EBV-driven lymphoproliferative disease. Oncotarget 6, 2693–2708 (2015). This study examines the effects of the translation inhibitor and stress granule inducer silvestrol on innate and adaptive immunity in vivo.

  121. 121.

    , , , & Fas-activated serine/threonine kinase (FAST) phosphorylates TIA-1 during Fas-mediated apoptosis. J. Exp. Med. 182, 865–874 (1995).

  122. 122.

    et al. The apoptosis-promoting factor TIA-1 is a regulator of alternative pre-mRNA splicing. Mol. Cell 6, 1089–1098 (2000).

  123. 123.

    et al. Inactivation of the mTORC1–eukaryotic translation initiation factor 4E pathway alters stress granule formation. Mol. Cell. Biol. 33, 2285–2301 (2013).

  124. 124.

    et al. Atomic force microscopy reveals binding of mRNA to microtubules mediated by two major mRNP proteins YB-1 and PABP. FEBS Lett. 582, 2875–2881 (2008).

  125. 125.

    , , , & Formation of stress granules inhibits apoptosis by suppressing stress-responsive MAPK pathways. Nat. Cell Biol. 10, 1324–1332 (2008).

  126. 126.

    et al. Antiviral protein APOBEC3G localizes to ribonucleoprotein complexes found in P bodies and stress granules. J. Virol. 81, 2165–2178 (2007).

  127. 127.

    et al. Human DDX3 protein is a valuable target to develop broad spectrum antiviral agents. Proc. Natl Acad. Sci. USA 113, 5388–5393 (2016).

  128. 128.

    et al. Regulation of human endonuclease V activity and relocalization to cytoplasmic stress granules. J. Biol. Chem. 291, 21786–21801 (2016).

  129. 129.

    , & Nuclear factor 90 is a substrate and regulator of the eukaryotic initiation factor 2 kinase double-stranded RNA-activated protein kinase. J. Biol. Chem. 276, 32522–32530 (2001).

Download references

Acknowledgements

This work was supported by grants to C.M. from the Natural Sciences and Engineering Research Council of Canada (RGPIN-341940) and the Canadian Institutes of Health Research (MOP-136817 and PJT-148727). The authors thank members of the McCormick laboratory for providing feedback on the manuscript.

Author information

Affiliations

  1. Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.

    • Craig McCormick
    •  & Denys A. Khaperskyy

Authors

  1. Search for Craig McCormick in:

  2. Search for Denys A. Khaperskyy in:

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Craig McCormick.

Glossary

Eukaryotic translation initiation factor 4F complex

(eIF4F complex). A complex formed from the translation initiation factors eIF4E, eIF4G and eIF4A bound to the 5′ cap of mRNA.

eIF2–GDP

The form of eukaryotic translation initiation factor 2 (eIF2) that needs to exchange GDP for GTP to be able to form the eIF2–GTP–Met–tRNAMet ternary complex that is required for subsequent rounds of translation initiation.

eIF2–GTP–Met–tRNAMet ternary complex

A translation initiation-competent complex that brings methionine amino-acyl tRNA to the 48S pre-initiation complex.

48S pre-initiation complex

A complex that is formed from mRNA, the eukaryotic translation initiation factors eIF4F, polyadenylate-binding protein 1, eIF3, eIF1, eIF1A, eIF5 and eIF2, and the 40S small ribosomal subunit, and that is poised for the recognition of the initiation codon and for the recruitment of the large ribosomal subunit.

Initiation codon

The first AUG triplet that is recognized by the tRNAMet anticodon.

Stalled 48S mRNPs

48S pre-initiation complexes that are unable to recruit the large ribosomal subunit and initiate polypeptide synthesis.

Pateamine A

A small-molecule inhibitor of the helicase function of eukaryotic translation initiation factor 4A. It is a natural product derived from marine sponges of the Mycale genus.

Polysome

A structure formed from mRNA bound by multiple elongating ribosomes.

Low complexity and intrinsically disordered domains

Regions or domains of proteins that have reduced diversity in terms of their amino acid composition, which exist in a disordered state.

Liquid–liquid phase separation

The formation of droplets that concentrate macromolecules such as proteins and RNA within an aqueous solution. Macromolecules are held within phase-separated droplets by multiple weak interactions while retaining the ability to diffuse in and out of the droplets.

HIV transactivation-response region RNA hairpins

RNA elements within the HIV genome that are the binding sites for the HIV trans-activator protein Tat and that form multiple secondary structures.

Internal ribosome entry sites

(IRESs). RNA elements that fold into secondary structures that function as platforms for the internal recruitment of the translation initiation machinery.

BirA

A biotin ligase from Escherichia coli that biotinylates acetyl-CoA carboxylase subunits. A mutant form of this enzyme that has a relaxed specificity is used in proximity-dependent biotin identification (BioID) proteomics.

APEX

In the context of this Review, refers to an engineered ascorbate peroxidase that is used for proximity-dependent biotin labelling in proteomics methods.

About this article

Publication history

Published

DOI

https://doi.org/10.1038/nri.2017.63

Further reading