Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Pushing the envelope: LPS modifications and their consequences

Abstract

The defining feature of the Gram-negative cell envelope is the presence of two cellular membranes, with the specialized glycolipid lipopolysaccharide (LPS) exclusively found on the surface of the outer membrane. The surface layer of LPS contributes to the stringent permeability properties of the outer membrane, which is particularly resistant to permeation of many toxic compounds, including antibiotics. As a common surface antigen, LPS is recognized by host immune cells, which mount defences to clear pathogenic bacteria. To alter properties of the outer membrane or evade the host immune response, Gram-negative bacteria chemically modify LPS in a wide variety of ways. Here, we review key features and physiological consequences of LPS biogenesis and modifications.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Fig. 1: Lipopolysaccharide biogenesis, structure and modifications.
Fig. 2: Regulation of lipopolysaccharide modifications.
Fig. 3: Consequences of lipopolysaccharide modifications.
Fig. 4: Summary of therapeutic strategies to target lipopolysaccharide biogenesis.

References

  1. Muhlradt, P. F. & Golecki, J. R. Asymmetrical distribution and artifactual reorientation of lipopolysaccharide in the outer membrane bilayer of Salmonella typhimurium. Eur. J. Biochem. 51, 343–352 (1975).

    CAS  PubMed  Google Scholar 

  2. Nikaido, H. & Vaara, M. Molecular basis of bacterial outer membrane permeability. Microbiol. Rev. 49, 1–32 (1985).

    CAS  PubMed  PubMed Central  Google Scholar 

  3. Whitfield, C. & Trent, M. S. Biosynthesis and export of bacterial lipopolysaccharides. Annu. Rev. Biochem. 83, 99–128 (2014).

    CAS  PubMed  Google Scholar 

  4. Muhlradt, P. F., Menzel, J., Golecki, J. R. & Speth, V. Outer membrane of Salmonella. Sites of export of newly synthesised lipopolysaccharide on the bacterial surface. Eur. J. Biochem. 35, 471–481 (1973).

    CAS  PubMed  Google Scholar 

  5. Osborn, M. J., Gander, J. E. & Parisi, E. Mechanism of assembly of the outer membrane of Salmonella typhimurium. Site of synthesis of lipopolysaccharide. J. Biol. Chem. 247, 3973–3986 (1972).

    CAS  PubMed  Google Scholar 

  6. Young, H. E. et al. Discovery of the elusive UDP-diacylglucosamine hydrolase in the lipid A biosynthetic pathway in Chlamydia trachomatis. mBio 7, e00090 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  7. Rubin, E. J., O’Brien, J. P., Ivanov, P. L., Brodbelt, J. S. & Trent, M. S. Identification of a broad family of lipid A late acyltransferases with non-canonical substrate specificity. Mol. Microbiol. 91, 887–899 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  8. Hankins, J. V. et al. Elucidation of a novel Vibrio cholerae lipid A secondary hydroxy-acyltransferase and its role in innate immune recognition. Mol. Microbiol. 81, 1313–1329 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  9. Okuda, S., Sherman, D. J., Silhavy, T. J., Ruiz, N. & Kahne, D. Lipopolysaccharide transport and assembly at the outer membrane: the PEZ model. Nat. Rev. Microbiol. 14, 337–345 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  10. Sweet, C. R. et al. Enzymatic synthesis of lipid A molecules with four amide-linked acyl chains. LpxA acyltransferases selective for an analog of UDP-N-acetylglucosamine in which an amine replaces the 3”-hydroxyl group. J. Biol. Chem. 279, 25411–25419 (2004).

    CAS  PubMed  Google Scholar 

  11. van Mourik, A. et al. Altered linkage of hydroxyacyl chains in lipid A of Campylobacter jejuni reduces TLR4 activation and antimicrobial resistance. J. Biol. Chem. 285, 15828–15836 (2010).

    PubMed  PubMed Central  Google Scholar 

  12. Gattis, S. G., Chung, H. S., Trent, M. S. & Raetz, C. R. The origin of 8-amino-3,8-dideoxy-D-manno-octulosonic acid (Kdo8N) in the lipopolysaccharide of Shewanella oneidensis. J. Biol. Chem. 288, 9216–9225 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  13. Belunis, C. J. & Raetz, C. R. Biosynthesis of endotoxins. Purification and catalytic properties of 3-deoxy-D-manno-octulosonic acid transferase from Escherichia coli. J. Biol. Chem. 267, 9988–9997 (1992).

    CAS  PubMed  Google Scholar 

  14. Hankins, J. V. & Trent, M. S. Secondary acylation of Vibrio cholerae lipopolysaccharide requires phosphorylation of Kdo. J. Biol. Chem. 284, 25804–25812 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  15. Lobau, S., Mamat, U., Brabetz, W. & Brade, H. Molecular cloning, sequence analysis, and functional characterization of the lipopolysaccharide biosynthetic gene kdtA encoding 3-deoxy-α-D-manno-octulosonic acid transferase of Chlamydia pneumoniae strain TW-183. Mol. Microbiol. 18, 391–399 (1995).

    CAS  PubMed  Google Scholar 

  16. Mamat, U., Baumann, M., Schmidt, G. & Brade, H. The genus-specific lipopolysaccharide epitope of Chlamydia is assembled in C. psittaci and C. trachomatis by glycosyltransferases of low homology. Mol. Microbiol. 10, 935–941 (1993).

    CAS  PubMed  Google Scholar 

  17. Chung, H. S. & Raetz, C. R. Dioxygenases in Burkholderia ambifaria and Yersinia pestis that hydroxylate the outer Kdo unit of lipopolysaccharide. Proc. Natl Acad. Sci. USA 108, 510–515 (2011).

    CAS  PubMed  Google Scholar 

  18. White, K. A., Lin, S., Cotter, R. J. & Raetz, C. R. A. Haemophilus influenzae gene that encodes a membrane bound 3-deoxy-D-manno-octulosonic acid (Kdo) kinase. Possible involvement of Kdo phosphorylation in bacterial virulence. J. Biol. Chem. 274, 31391–31400 (1999).

    CAS  PubMed  Google Scholar 

  19. Boll, J. M. et al. Reinforcing lipid A acylation on the cell surface of Acinetobacter baumannii promotes cationic antimicrobial peptide resistance and desiccation survival. mBio 6, e00478–15 (2015). This study identified secondary acyltransferases in A. baumannii , including an unusual, dual-functioning LpxM that catalyses transfer of acyl chains to two positions.

    CAS  PubMed  PubMed Central  Google Scholar 

  20. Eshghi, A., Henderson, J., Trent, M. S. & Picardeau, M. Leptospira interrogans lpxD homologue is required for thermal acclimatization and virulence. Infect. Immun. 83, 4314–4321 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  21. Li, Y. et al. LPS remodeling is an evolved survival strategy for bacteria. Proc. Natl Acad. Sci. USA 109, 8716–8721 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  22. Guo, L. et al. Lipid A acylation and bacterial resistance against vertebrate antimicrobial peptides. Cell 95, 189–198 (1998).

    CAS  PubMed  Google Scholar 

  23. Reynolds, C. M. et al. An outer membrane enzyme encoded by Salmonella typhimurium lpxR that removes the 3´-acyloxyacyl moiety of lipid A. J. Biol. Chem. 281, 21974–21987 (2006).

    CAS  PubMed  Google Scholar 

  24. Trent, M. S., Ribeiro, A. A., Lin, S., Cotter, R. J. & Raetz, C. R. An inner membrane enzyme in Salmonella and Escherichia coli that transfers 4-amino-4-deoxy-L-arabinose to lipid A: induction on polymyxin-resistant mutants and role of a novel lipid-linked donor. J. Biol. Chem. 276, 43122–43131 (2001).

    CAS  PubMed  Google Scholar 

  25. Gibbons, H. S., Lin, S., Cotter, R. J. & Raetz, C. R. Oxygen requirement for the biosynthesis of the S-2-hydroxymyristate moiety in Salmonella typhimurium lipid A. Function of LpxO, A new Fe2+/α-ketoglutarate-dependent dioxygenase homologue. J. Biol. Chem. 275, 32940–32949 (2000).

    CAS  PubMed  Google Scholar 

  26. Hankins, J. V., Madsen, J. A., Giles, D. K., Brodbelt, J. S. & Trent, M. S. Amino acid addition to Vibrio cholerae LPS establishes a link between surface remodeling in gram-positive and gram-negative bacteria. Proc. Natl Acad. Sci. USA 109, 8722–8727 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  27. Needham, B. D. & Trent, M. S. Fortifying the barrier: the impact of lipid A remodelling on bacterial pathogenesis. Nat. Rev. Microbiol. 11, 467–481 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  28. Kanistanon, D. et al. A Francisella mutant in lipid A carbohydrate modification elicits protective immunity. PLOS Pathog. 4, e24 (2008).

    PubMed  PubMed Central  Google Scholar 

  29. Herrera, C. M., Hankins, J. V. & Trent, M. S. Activation of PmrA inhibits LpxT-dependent phosphorylation of lipid A promoting resistance to antimicrobial peptides. Mol. Microbiol. 76, 1444–1460 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  30. Nowicki, E. M., O’Brien, J. P., Brodbelt, J. S. & Trent, M. S. Characterization of Pseudomonas aeruginosa LpxT reveals dual positional lipid A kinase activity and co-ordinated control of outer membrane modification. Mol. Microbiol. 94, 728–741 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  31. Lerouge, I. & Vanderleyden, J. O-Antigen structural variation: mechanisms and possible roles in animal/plant-microbe interactions. FEMS Microbiol. Rev. 26, 17–47 (2002).

    CAS  PubMed  Google Scholar 

  32. Samuel, G. & Reeves, P. Biosynthesis of O-antigens: genes and pathways involved in nucleotide sugar precursor synthesis and O-antigen assembly. Carbohydr. Res. 338, 2503–2519 (2003).

    CAS  PubMed  Google Scholar 

  33. Stead, C. et al. A novel 3-deoxy-D-manno-octulosonic acid (Kdo) hydrolase that removes the outer Kdo sugar of Helicobacter pylori lipopolysaccharide. J. Bacteriol. 187, 3374–3383 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  34. Stead, C. M., Beasley, A., Cotter, R. J. & Trent, M. S. Deciphering the unusual acylation pattern of Helicobacter pylori lipid A. J. Bacteriol. 190, 7012–7021 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  35. Tran, A. X. et al. Periplasmic cleavage and modification of the 1-phosphate group of Helicobacter pylori lipid A. J. Biol. Chem. 279, 55780–55791 (2004).

    CAS  PubMed  Google Scholar 

  36. Tran, A. X., Stead, C. M. & Trent, M. S. Remodeling of Helicobacter pylori lipopolysaccharide. J. Endotoxin Res. 11, 161–166 (2005).

    CAS  PubMed  Google Scholar 

  37. Chen, H. D. & Groisman, E. A. The biology of the PmrA/PmrB two-component system: the major regulator of lipopolysaccharide modifications. Annu. Rev. Microbiol. 67, 83–112 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  38. Prost, L. R. & Miller, S. I. The Salmonellae PhoQ sensor: mechanisms of detection of phagosome signals. Cell. Microbiol. 10, 576–582 (2008).

    CAS  PubMed  Google Scholar 

  39. Garcia Vescovi, E., Soncini, F. C. & Groisman, E. A. Mg2+ as an extracellular signal: environmental regulation of Salmonella virulence. Cell 84, 165–174 (1996).

    CAS  PubMed  Google Scholar 

  40. Richards, S. M., Strandberg, K. L., Conroy, M. & Gunn, J. S. Cationic antimicrobial peptides serve as activation signals for the Salmonella Typhimurium PhoPQ and PmrAB regulons in vitro and in vivo. Front. Cell. Infect. Microbiol. 2, 102 (2012).

    PubMed  PubMed Central  Google Scholar 

  41. Yuan, J., Jin, F., Glatter, T. & Sourjik, V. Osmosensing by the bacterial PhoQ/PhoP two-component system. Proc. Natl Acad. Sci. USA 114, E10792–E10798 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  42. Gooderham, W. J. et al. The sensor kinase PhoQ mediates virulence in Pseudomonas aeruginosa. Microbiology 155, 699–711 (2009).

    CAS  PubMed  Google Scholar 

  43. Bader, M. W. et al. Recognition of antimicrobial peptides by a bacterial sensor kinase. Cell 122, 461–472 (2005).

    CAS  PubMed  Google Scholar 

  44. Prost, L. R. et al. Activation of the bacterial sensor kinase PhoQ by acidic pH. Mol. Cell 26, 165–174 (2007).

    CAS  PubMed  Google Scholar 

  45. Choi, J. & Groisman, E. A. Acidic pH sensing in the bacterial cytoplasm is required for Salmonella virulence. Mol. Microbiol. 101, 1024–1038 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  46. Choi, J. & Groisman, E. A. Activation of master virulence regulator PhoP in acidic pH requires the Salmonella-specific protein UgtL. Sci. Signal. 10, eaan6284 (2017).

    PubMed  PubMed Central  Google Scholar 

  47. Guo, L. et al. Regulation of lipid A modifications by Salmonella typhimurium virulence genes phoP-phoQ. Science 276, 250–253 (1997).

    CAS  PubMed  Google Scholar 

  48. Kox, L. F., Wosten, M. M. & Groisman, E. A. A small protein that mediates the activation of a two-component system by another two-component system. EMBO J. 19, 1861–1872 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  49. Rubin, E. J., Herrera, C. M., Crofts, A. A. & Trent, M. S. PmrD is required for modifications to Escherichia coli endotoxin that promote antimicrobial resistance. Antimicrob. Agents Chemother. 59, 2051–2061 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  50. Kato, A. & Groisman, E. A. Connecting two-component regulatory systems by a protein that protects a response regulator from dephosphorylation by its cognate sensor. Genes Dev. 18, 2302–2313 (2004).

    CAS  PubMed  PubMed Central  Google Scholar 

  51. Lippa, A. M. & Goulian, M. Feedback inhibition in the PhoQ/PhoP signaling system by a membrane peptide. PLOS Genet. 5, e1000788 (2009).

    PubMed  PubMed Central  Google Scholar 

  52. Wosten, M. M., Kox, L. F., Chamnongpol, S., Soncini, F. C. & Groisman, E. A. A signal transduction system that responds to extracellular iron. Cell 103, 113–125 (2000).

    CAS  PubMed  Google Scholar 

  53. Perez, J. C. & Groisman, E. A. Acid pH activation of the PmrA/PmrB two-component regulatory system of Salmonella enterica. Mol. Microbiol. 63, 283–293 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  54. Kato, A., Chen, H. D., Latifi, T. & Groisman, E. A. Reciprocal control between a bacterium’s regulatory system and the modification status of its lipopolysaccharide. Mol. Cell 47, 897–908 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  55. Fernandez, P. A. et al. Fnr and ArcA regulate lipid A hydroxylation in Salmonella enteritidis by controlling lpxO expression in response to oxygen availability. Front. Microbiol. 9, 1220 (2018).

    PubMed  PubMed Central  Google Scholar 

  56. Nowicki, E. M., O’Brien, J. P., Brodbelt, J. S. & Trent, M. S. Extracellular zinc induces phosphoethanolamine addition to Pseudomonas aeruginosa lipid A via the ColRS two-component system. Mol. Microbiol. 97, 166–178 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  57. Fernandez, L. et al. Adaptive resistance to the “last hope” antibiotics polymyxin B and colistin in Pseudomonas aeruginosa is mediated by the novel two-component regulatory system ParR-ParS. Antimicrob. Agents Chemother. 54, 3372–3382 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  58. Fernandez, L. et al. The two-component system CprRS senses cationic peptides and triggers adaptive resistance in Pseudomonas aeruginosa independently of ParRS. Antimicrob. Agents Chemother. 56, 6212–6222 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  59. Bilecen, K. et al. Polymyxin B resistance and biofilm formation in Vibrio cholerae are controlled by the response regulator CarR. Infect. Immun. 83, 1199–1209 (2015).

    PubMed  PubMed Central  Google Scholar 

  60. Herrera, C. M. et al. The Vibrio cholerae VprA-VprB. two-component system controls virulence through endotoxin modification. mBio 5, e02283–14 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  61. Cheng, Y. H., Lin, T. L., Lin, Y. T. & Wang, J. T. Amino acid substitutions of CrrB responsible for resistance to colistin through CrrC in Klebsiella pneumoniae. Antimicrob. Agents Chemother. 60, 3709–3716 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  62. Coornaert, A. et al. MicA sRNA links the PhoP regulon to cell envelope stress. Mol. Microbiol. 76, 467–479 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  63. Moon, K. & Gottesman, S. A. PhoQ/P-regulated small RNA regulates sensitivity of Escherichia coli to antimicrobial peptides. Mol. Microbiol. 74, 1314–1330 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  64. Kawasaki, K., Ernst, R. K. & Miller, S. I. Inhibition of Salmonella enterica serovar Typhimurium lipopolysaccharide deacylation by aminoarabinose membrane modification. J. Bacteriol. 187, 2448–2457 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  65. Reines, M. et al. Deciphering the acylation pattern of Yersinia enterocolitica lipid A. PLoS Pathog. 8, e1002978 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  66. Bishop, R. E. et al. Transfer of palmitate from phospholipids to lipid A in outer membranes of Gram-negative bacteria. EMBO J. 19, 5071–5080 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  67. Jia, W. et al. Lipid trafficking controls endotoxin acylation in outer membranes of Escherichia coli. J. Biol. Chem. 279, 44966–44975 (2004).

    CAS  PubMed  Google Scholar 

  68. Murata, T., Tseng, W., Guina, T., Miller, S. I. & Nikaido, H. PhoPQ-mediated regulation produces a more robust permeability barrier in the outer membrane of Salmonella enterica serovar typhimurium. J. Bacteriol. 189, 7213–7222 (2007). LPS modifications upregulated by PhoPQ and PmrAB alter the permeability of the outer membrane to be more stable in Mg 2+ -limiting environments but less stable in high-Mg 2+ -concentration environments.

    CAS  PubMed  PubMed Central  Google Scholar 

  69. Sassi, N., Paul, C., Martin, A., Bettaieb, A. & Jeannin, J. F. Lipid A-induced responses in vivo. Adv. Exp. Med. Biol. 667, 69–80 (2010).

    PubMed  Google Scholar 

  70. Kong, Q. et al. Palmitoylation state impacts induction of innate and acquired immunity by the Salmonella enterica serovar Typhimurium msbB mutant. Infect. Immun. 79, 5027–5038 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  71. Kong, Q. et al. Phosphate groups of lipid A are essential for Salmonella enterica serovar Typhimurium virulence and affect innate and adaptive immunity. Infect. Immun. 80, 3215–3224 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  72. Casella, C. R. & Mitchell, T. C. Putting endotoxin to work for us: monophosphoryl lipid A as a safe and effective vaccine adjuvant. Cell. Mol. Life Sci. 65, 3231–3240 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  73. Yamamoto, M. & Akira, S. Lipid A receptor TLR4-mediated signaling pathways. Adv. Exp. Med. Biol. 667, 59–68 (2010).

    PubMed  Google Scholar 

  74. Cullen, T. W. et al. Helicobacter pylori versus the host: remodeling of the bacterial outer membrane is required for survival in the gastric mucosa. PLOS Pathog. 7, e1002454 (2011).

    CAS  PubMed  PubMed Central  Google Scholar 

  75. Mandell, L. et al. Intact gram-negative Helicobacter pylori, Helicobacter felis, and Helicobacter hepaticus bacteria activate innate immunity via toll-like receptor 2 but not toll-like receptor 4. Infect. Immun. 72, 6446–6454 (2004).

    CAS  PubMed  PubMed Central  Google Scholar 

  76. Llobet, E. et al. Deciphering tissue-induced Klebsiella pneumoniae lipid A structure. Proc. Natl Acad. Sci. USA 112, E6369–E6378 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  77. Shi, J. et al. Inflammatory caspases are innate immune receptors for intracellular LPS. Nature 514, 187–192 (2014).

    CAS  PubMed  Google Scholar 

  78. Hagar, J. A., Powell, D. A., Aachoui, Y., Ernst, R. K. & Miao, E. A. Cytoplasmic LPS activates caspase-11: implications in TLR4-independent endotoxic shock. Science 341, 1250–1253 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  79. Kayagaki, N. et al. Noncanonical inflammasome activation by intracellular LPS independent of TLR4. Science 341, 1246–1249 (2013). Along with reference 78, this study discovered that murine caspase 11 interacts with cytoplasmic LPS and stimulates the inflammasome independently of TLR4.

    CAS  PubMed  Google Scholar 

  80. Guo, H., Callaway, J. B. & Ting, J. P. Inflammasomes: mechanism of action, role in disease, and therapeutics. Nat. Med. 21, 677–687 (2015).

    PubMed  PubMed Central  Google Scholar 

  81. Lagrange, B. et al. Human caspase-4 detects tetra-acylated LPS and cytosolic Francisella and functions differently from murine caspase-11. Nat. Commun. 9, 242 (2018).

    PubMed  PubMed Central  Google Scholar 

  82. Peschel, A. & Sahl, H. G. The co-evolution of host cationic antimicrobial peptides and microbial resistance. Nat. Rev. Microbiol. 4, 529–536 (2006).

    CAS  PubMed  Google Scholar 

  83. Faith, J. J. et al. The long-term stability of the human gut microbiota. Science 341, 1237439 (2013).

    PubMed  PubMed Central  Google Scholar 

  84. Cullen, T. W. et al. Gut microbiota. Antimicrobial peptide resistance mediates resilience of prominent gut commensals during inflammation. Science 347, 170–175 (2015). LPS modifications that mediate AMP resistance contribute to stable maintenance of the gut microbiota.

    CAS  PubMed  PubMed Central  Google Scholar 

  85. Schwarz, S. & Johnson, A. P. Transferable resistance to colistin: a new but old threat. J. Antimicrob. Chemother. 71, 2066–2070 (2016).

    PubMed  Google Scholar 

  86. Schwechheimer, C. & Kuehn, M. J. Outer-membrane vesicles from Gram-negative bacteria: biogenesis and functions. Nat. Rev. Microbiol. 13, 605–619 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  87. Haurat, M. F. et al. Selective sorting of cargo proteins into bacterial membrane vesicles. J. Biol. Chem. 286, 1269–1276 (2011).

    CAS  PubMed  Google Scholar 

  88. Horstman, A. L. & Kuehn, M. J. Enterotoxigenic Escherichia coli secretes active heat-labile enterotoxin via outer membrane vesicles. J. Biol. Chem. 275, 12489–12496 (2000).

    CAS  PubMed  Google Scholar 

  89. Horstman, A. L., Bauman, S. J. & Kuehn, M. J. Lipopolysaccharide 3-deoxy-D-manno-octulosonic acid (Kdo) core determines bacterial association of secreted toxins. J. Biol. Chem. 279, 8070–8075 (2004).

    CAS  PubMed  Google Scholar 

  90. Chen, Y. Y. et al. The outer membrane protein LptO is essential for the O-deacylation of LPS and the co-ordinated secretion and attachment of A-LPS and CTD proteins in Porphyromonas gingivalis. Mol. Microbiol. 79, 1380–1401 (2011).

    CAS  PubMed  Google Scholar 

  91. Rangarajan, M. et al. LptO (PG0027) is required for lipid A 1-phosphatase activity in Porphyromonas gingivalis W50. J. Bacteriol. 199, e00751–16 (2017).

    PubMed  PubMed Central  Google Scholar 

  92. Sato, K. et al. Identification of Porphyromonas gingivalis proteins secreted by the Por secretion system. FEMS Microbiol. Lett. 338, 68–76 (2013).

    CAS  PubMed  Google Scholar 

  93. Gabarrini, G. et al. Conserved citrullinating exoenzymes in Porphyromonas species. J. Dent. Res. 97, 556–562 (2018).

    CAS  PubMed  Google Scholar 

  94. Konig, M. F. et al. Defining the role of Porphyromonas gingivalis peptidylarginine deiminase (PPAD) in rheumatoid arthritis through the study of PPAD biology. Ann. Rheum. Dis. 74, 2054–2061 (2015).

    CAS  PubMed  Google Scholar 

  95. Wegner, N. et al. Autoimmunity to specific citrullinated proteins gives the first clues to the etiology of rheumatoid arthritis. Immunol. Rev. 233, 34–54 (2010).

    CAS  PubMed  Google Scholar 

  96. Gabarrini, G. et al. Dropping anchor: attachment of peptidylarginine deiminase via A-LPS to secreted outer membrane vesicles of Porphyromonas gingivalis. Sci. Rep. 8, 8949 (2018).

    PubMed  PubMed Central  Google Scholar 

  97. Gabarrini, G. et al. There’s no place like OM: vesicular sorting and secretion of the peptidylarginine deiminase of Porphyromonas gingivalis. Virulence 9, 456–464 (2018).

    PubMed  PubMed Central  Google Scholar 

  98. Mashburn-Warren, L. et al. Interaction of quorum signals with outer membrane lipids: insights into prokaryotic membrane vesicle formation. Mol. Microbiol. 69, 491–502 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  99. Li, A., Schertzer, J. W. & Yong, X. Molecular conformation affects the interaction of the Pseudomonas quinolone signal with the bacterial outer membrane. J. Biol. Chem. 294, 1089–1094 (2018).

    PubMed  PubMed Central  Google Scholar 

  100. Elhenawy, W. et al. LPS remodeling triggers formation of outer membrane vesicles in Salmonella. mBio 7, e00940–16 (2016). PagL-mediated deacylation of LPS in S . Typhimurium stimulates production of OMVs.

    CAS  PubMed  PubMed Central  Google Scholar 

  101. Bonnington, K. E. & Kuehn, M. J. Outer membrane vesicle production facilitates LPS remodeling and outer membrane maintenance in Salmonella during environmental transitions. mBio 7, e01532–16 (2016). During environmental transitions that alter LPS modification, certain LPS species are selectively secreted and others are under-represented in OMVs.

    CAS  PubMed  PubMed Central  Google Scholar 

  102. Cipolla, L. et al. New targets for antibacterial design: Kdo biosynthesis and LPS machinery transport to the cell surface. Curr. Med. Chem. 18, 830–852 (2011).

    CAS  PubMed  Google Scholar 

  103. Zhou, P. & Zhao, J. Structure, inhibition, and regulation of essential lipid A enzymes. Biochim. Biophys. Acta Mol. Cell Biol. Lipids 1862, 1424–1438 (2017).

    CAS  PubMed  Google Scholar 

  104. Erwin, A. L. Antibacterial drug discovery targeting the lipopolysaccharide biosynthetic enzyme LpxC. Cold Spring Harb. Perspect. Med. 6, a025304 (2016).

    PubMed  PubMed Central  Google Scholar 

  105. Richie, D. L. et al. Toxic accumulation of LPS pathway intermediates underlies the requirement of LpxH for growth of Acinetobacter baumannii ATCC 19606. PLOS ONE 11, e0160918 (2016).

    PubMed  PubMed Central  Google Scholar 

  106. Wei, J. R. et al. LpxK is essential for growth of Acinetobacter baumannii ATCC 19606: relationship to toxic accumulation of lipid A pathway intermediates. mSphere 2, e00199–17 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  107. Piizzi, G. et al. Design, synthesis, and properties of a potent inhibitor of Pseudomonas aeruginosa deacetylase LpxC. J. Med. Chem. 60, 5002–5014 (2017).

    CAS  PubMed  Google Scholar 

  108. Pratap, S. et al. Acyl chain preference and inhibitor identification of Moraxella catarrhalis LpxA: Insight through crystal structure and computational studies. Int. J. Biol. Macromol. 96, 759–765 (2017).

    CAS  PubMed  Google Scholar 

  109. Nayar, A. S. et al. Novel antibacterial targets and compounds revealed by a high-throughput cell wall reporter assay. J. Bacteriol. 197, 1726–1734 (2015).

    CAS  PubMed  PubMed Central  Google Scholar 

  110. Richie, D. L. et al. A pathway-directed positive growth restoration assay to facilitate the discovery of lipid A and fatty acid biosynthesis inhibitors in Acinetobacter baumannii. PLOS ONE 13, e0193851 (2018).

    PubMed  PubMed Central  Google Scholar 

  111. Ho, H. et al. Structural basis for dual-mode inhibition of the ABC transporter MsbA. Nature 557, 196–201 (2018).

    CAS  PubMed  Google Scholar 

  112. Zhang, G. et al. Cell-based screen for discovering lipopolysaccharide biogenesis inhibitors. Proc. Natl Acad. Sci. USA 115, 6834–6839 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  113. May, J. M. et al. The antibiotic novobiocin binds and activates the ATPase that powers lipopolysaccharide transport. J. Am. Chem. Soc. 139, 17221–17224 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  114. Mandler, M. D. et al. Novobiocin enhances polymyxin activity by stimulating lipopolysaccharide transport. J. Am. Chem. Soc. 140, 6749–6753 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  115. Srinivas, N. et al. Peptidomimetic antibiotics target outer-membrane biogenesis in Pseudomonas aeruginosa. Science 327, 1010–1013 (2010).

    CAS  PubMed  Google Scholar 

  116. Vetterli, S. U., Moehle, K. & Robinson, J. A. Synthesis and antimicrobial activity against Pseudomonas aeruginosa of macrocyclic beta-hairpin peptidomimetic antibiotics containing N-methylated amino acids. Bioorg. Med. Chem. 24, 6332–6339 (2016).

    CAS  PubMed  Google Scholar 

  117. Werneburg, M. et al. Inhibition of lipopolysaccharide transport to the outer membrane in Pseudomonas aeruginosa by peptidomimetic antibiotics. Chembiochem 13, 1767–1775 (2012).

    CAS  PubMed  Google Scholar 

  118. Vetterli, S. U. et al. Thanatin targets the intermembrane protein complex required for lipopolysaccharide transport in Escherichia coli. Sci. Adv. 4, eaau2634 (2018).

    PubMed  PubMed Central  Google Scholar 

  119. Zhang, X. et al. Identification of an anti-Gram-negative bacteria agent disrupting the interaction between LPS transporters LptA and LptC. Int. J. Antimicrob. Agents 53, 442–448 (2018).

    PubMed  Google Scholar 

  120. Harris, T. L. et al. Small molecule downregulation of PmrAB reverses lipid A modification and breaks colistin resistance. ACS Chem. Biol. 9, 122–127 (2014).

    CAS  PubMed  Google Scholar 

  121. Kline, T. et al. Synthesis of and evaluation of lipid A modification by 4-substituted 4-deoxy arabinose analogs as potential inhibitors of bacterial polymyxin resistance. Bioorg. Med. Chem. Lett. 18, 1507–1510 (2008).

    CAS  PubMed  Google Scholar 

  122. Anandan, A. et al. Structure of a lipid A phosphoethanolamine transferase suggests how conformational changes govern substrate binding. Proc. Natl Acad. Sci. USA 114, 2218–2223 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  123. Touze, T., Tran, A. X., Hankins, J. V., Mengin-Lecreulx, D. & Trent, M. S. Periplasmic phosphorylation of lipid A is linked to the synthesis of undecaprenyl phosphate. Mol. Microbiol. 67, 264–277 (2008).

    CAS  PubMed  Google Scholar 

  124. Cullen, T. W. et al. EptC of Campylobacter jejuni mediates phenotypes involved in host interactions and virulence. Infect. Immun. 81, 430–440 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  125. Cullen, T. W. & Trent, M. S. A link between the assembly of flagella and lipooligosaccharide of the Gram-negative bacterium Campylobacter jejuni. Proc. Natl Acad. Sci. USA 107, 5160–5165 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  126. Bach, J. F. & Chatenoud, L. The hygiene hypothesis: an explanation for the increased frequency of insulin-dependent diabetes. Cold Spring Harb. Perspect. Med. 2, a007799 (2012).

    PubMed  PubMed Central  Google Scholar 

  127. Vatanen, T. et al. Variation in microbiome LPS immunogenicity contributes to autoimmunity in humans. Cell 165, 1551 (2016).

    CAS  PubMed  Google Scholar 

  128. Raetz, C. R., Reynolds, C. M., Trent, M. S. & Bishop, R. E. Lipid A modification systems in gram-negative bacteria. Annu. Rev. Biochem. 76, 295–329 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  129. Moffatt, J. H. et al. Colistin resistance in Acinetobacter baumannii is mediated by complete loss of lipopolysaccharide production. Antimicrob. Agents Chemother. 54, 4971–4977 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  130. Peng, D., Hong, W., Choudhury, B. P., Carlson, R. W. & Gu, X. X. Moraxella catarrhalis bacterium without endotoxin, a potential vaccine candidate. Infect. Immun. 73, 7569–7577 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  131. Steeghs, L. et al. Meningitis bacterium is viable without endotoxin. Nature 392, 449–450 (1998).

    CAS  PubMed  Google Scholar 

  132. Beceiro, A. et al. Biological cost of different mechanisms of colistin resistance and their impact on virulence in Acinetobacter baumannii. Antimicrob. Agents Chemother. 58, 518–526 (2014).

    PubMed  PubMed Central  Google Scholar 

  133. Boll, J. M. et al. A penicillin-binding protein inhibits selection of colistin-resistant, lipooligosaccharide-deficient Acinetobacter baumannii. Proc. Natl Acad. Sci. USA 113, E6228–E6237 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  134. Henry, R. et al. Colistin-resistant, lipopolysaccharide-deficient Acinetobacter baumannii responds to lipopolysaccharide loss through increased expression of genes involved in the synthesis and transport of lipoproteins, phospholipids, and poly-beta-1,6-N-acetylglucosamine. Antimicrob. Agents Chemother. 56, 59–69 (2012).

    CAS  PubMed  PubMed Central  Google Scholar 

  135. Powers, M. J. & Trent, M. S. Phospholipid retention in the absence of asymmetry strengthens the outer membrane permeability barrier to last-resort antibiotics. Proc. Natl Acad. Sci. USA 115, E8518–E8527 (2018).

    CAS  PubMed  PubMed Central  Google Scholar 

  136. Qureshi, N., Takayama, K. & Ribi, E. Purification and structural determination of nontoxic lipid A obtained from the lipopolysaccharide of Salmonella typhimurium. J. Biol. Chem. 257, 11808–11815 (1982).

    CAS  PubMed  Google Scholar 

  137. Needham, B. D. et al. Modulating the innate immune response by combinatorial engineering of endotoxin. Proc. Natl Acad. Sci. USA 110, 1464–1469 (2013).

    CAS  PubMed  PubMed Central  Google Scholar 

  138. Gregg, K. A. et al. Rationally designed TLR4 ligands for vaccine adjuvant discovery. mBio 8, e00492–17 (2017).

    CAS  PubMed  PubMed Central  Google Scholar 

  139. Zariri, A., Pupo, E., van Riet, E., van Putten, J. P. & van der Ley, P. Modulating endotoxin activity by combinatorial bioengineering of meningococcal lipopolysaccharide. Sci. Rep. 6, 36575 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  140. Sanders, H. & Feavers, I. M. Adjuvant properties of meningococcal outer membrane vesicles and the use of adjuvants in Neisseria meningitidis protein vaccines. Expert Rev. Vaccines 10, 323–334 (2011).

    CAS  PubMed  Google Scholar 

  141. Price, N. L. et al. Glycoengineered outer membrane vesicles: a novel platform for bacterial vaccines. Sci. Rep. 6, 24931 (2016). This study engineered non-pathogenic E. coli to produce LPS modified with glycans from pathogenic bacteria, such as capsule from Streptococcus pneumoniae and heptasaccharide N -glycan from C. jejuni, that can be isolated in OMVs and used as vaccines.

    CAS  PubMed  PubMed Central  Google Scholar 

  142. Chen, L. et al. Outer membrane vesicles displaying engineered glycotopes elicit protective antibodies. Proc. Natl Acad. Sci. USA 113, E3609–E3618 (2016). This study engineered non-pathogenic E. coli to produce LPS modified with glycans from pathogenic bacteria, such as O antigen from F. tularensis subsp. tularensis, that can be isolated in OMVs and used as vaccines.

    CAS  PubMed  PubMed Central  Google Scholar 

  143. Valentine, J. L. et al. Immunization with outer membrane vesicles displaying designer glycotopes yields class-switched, glycan-specific antibodies. Cell Chem. Biol. 23, 655–665 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  144. Zhou, Z., White, K. A., Polissi, A., Georgopoulos, C. & Raetz, C. R. Function of Escherichia coli MsbA, an essential ABC family transporter, in lipid A and phospholipid biosynthesis. J. Biol. Chem. 273, 12466–12475 (1998).

    CAS  PubMed  Google Scholar 

  145. Mamat, U. et al. Single amino acid substitutions in either YhjD or MsbA confer viability to 3-deoxy-d-manno-oct-2-ulosonic acid-depleted Escherichia coli. Mol. Microbiol. 67, 633–648 (2008).

    CAS  PubMed  Google Scholar 

  146. Mi, W. et al. Structural basis of MsbA-mediated lipopolysaccharide transport. Nature 549, 233–237 (2017). This structural snapshot of MsbA 2 in complex with LPS suggests a ‘trap and flip’ model for LPS flipping across the inner membrane.

    CAS  PubMed  PubMed Central  Google Scholar 

  147. Ortega, X. P. et al. A putative gene cluster for aminoarabinose biosynthesis is essential for Burkholderia cenocepacia viability. J. Bacteriol. 189, 3639–3644 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  148. Hamad, M. A., Di Lorenzo, F., Molinaro, A. & Valvano, M. A. Aminoarabinose is essential for lipopolysaccharide export and intrinsic antimicrobial peptide resistance in Burkholderia cenocepacia. Mol. Microbiol. 85, 962–974 (2012).

    CAS  PubMed  Google Scholar 

  149. Bertani, B. R., Taylor, R. J., Nagy, E., Kahne, D. & Ruiz, N. A cluster of residues in the lipopolysaccharide exporter that selects substrate variants for transport to the outer membrane. Mol. Microbiol. 109, 541–554 (2018). In E. coli , extraction of LPS from the inner membrane by the LPS transporter requires interactions with the 1 and 4′ positions of lipid A.

    CAS  PubMed  PubMed Central  Google Scholar 

  150. Li, Y., Orlando, B. J. & Liao, M. Structural basis of lipopolysaccharide extraction by the LptB2FGC complex. Nature 567, 486–490 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  151. Owens, T. W. et al. Structural basis of unidirectional export of lipopolysaccharide to the cell surface. Nature 567, 550–553 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

Download references

Acknowledgements

The authors gratefully acknowledge funding from the National Institutes of Health (RO1s AI129940, AI138576, AI076322 to M.S.T.)

Reviewer information

Nature Reviews Microbiology thanks Mario Feldman, Marcin Grabowicz and Alessandra Polissi for their contribution to the peer review of this work.

Author information

Authors and Affiliations

Authors

Contributions

Both authors researched data for the article, discussed the content, wrote the article and reviewed and edited the manuscript before submission.

Corresponding author

Correspondence to M. Stephen Trent.

Ethics declarations

Competing interests

The authors declare no conflicts of interest.

Additional information

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Glossary

Lipooligosaccharide

(LOS). A form of lipopolysaccharide with an extended core oligosaccharide, but lacking O antigen.

Outer membrane vesicles

(OMVs). Small, spherical outer membrane blebs that are released from Gram-negative bacterial cells and contain membrane and periplasmic components.

Small RNAs

(sRNAs). Typically short, non-coding RNA molecules that interact with mRNAs to regulate gene expression or interact with proteins to regulate activity.

Inflammasome

An intracellular, multiprotein complex in mammalian cells that recognizes microbial molecules and activates inflammatory responses, including pyroptosis and proinflammatory cytokines.

Toll-like receptor 4–myeloid differentiation factor 2

(TLR4–MD2). A pattern-recognition receptor of the innate immune system that recognizes lipopolysaccharide and lipooligosaccharide, initiating a robust signal cascade and inflammatory responses in mammals.

Pyroptosis

An inflammatory, programmed cell death that typically is associated with infection of intracellular pathogens.

Capsule

A thick layer of polysaccharides that surrounds a bacterial cell, also referred to as capsular polysaccharide.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Simpson, B.W., Trent, M.S. Pushing the envelope: LPS modifications and their consequences. Nat Rev Microbiol 17, 403–416 (2019). https://doi.org/10.1038/s41579-019-0201-x

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41579-019-0201-x

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing