Neisseria gonorrhoeae virulence factor NG1686 is a bifunctional M23B family metallopeptidase that influences resistance to hydrogen peroxide and colony morphology

Elizabeth A. Stohl*, Yolande A. Chan, Kathleen T. Hackett, Petra L. Kohler, Joseph P. Dillard, H. Steven Seifert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Symptomatic gonococcal infection, caused exclusively by the human-specific pathogen Neisseria gonorrhoeae (the gonococcus), is characterized by the influx of polymorphonuclear leukocytes (PMNs) to the site of infection. Although PMNs possess a potent antimicrobial arsenal comprising both oxidative and non-oxidative killing mechanisms, gonococci survive this interaction, suggesting that the gonococcus has evolved many defenses against PMN killing. We previously identified the NG1686 protein as a gonococcal virulence factor that protects against both non-oxidative PMN-mediated killing and oxidative killing by hydrogen peroxide. In this work, we show that deletion of ng1686 affects gonococcal colony morphology but not cell morphology and that overexpression of ng1686 does not confer enhanced survival to hydrogen peroxide on gonococci. NG1686 contains M23B endopeptidase active sites found in proteins that cleave bacterial cell wall peptidoglycan. Strains of N. gonorrhoeae expressing mutant NG1686 proteins with substitutions in many, but not all, conserved metallopeptidase active sites recapitulated the hydrogen peroxide sensitivity and altered colony morphology of the Δng1686 mutant strain. We showed that purified NG1686 protein degrades peptidoglycan in vitro and that mutations in many conserved active site residues abolished its degradative activity. Finally, we demonstrated that NG1686 possesses both DD-carboxypeptidase and endopeptidase activities. We conclude that the NG1686 protein is a M23B peptidase with dual activities that targets the cell wall to affect colony morphology and resistance to hydrogen peroxide and PMN-mediated killing.

Original languageEnglish (US)
Pages (from-to)11222-11233
Number of pages12
JournalJournal of Biological Chemistry
Volume287
Issue number14
DOIs
StatePublished - Mar 30 2012

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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