TABLE 1.

Defenses and regulators of the oxidative stress response of N. gonorrhoeae

Protein nameFunctionGene identification no.aLocation(s)bSensitivity of mutant strain (assay compound[s])cRegulation (details of interest)dReference(s)
Oxidative stress defenses
    SodBSuperoxide dismutase BNG0405C x (PQ, X/XO)+ (Fur/high Fe, H2O2) 9, 226, 236
    KatACatalaseNG1767C s (H2O2)+ (OxyR, H2O2) 107, 226, 262
    MntABC/MnABC-type Mn transporterNG0168P, IM s (PQ, H2O2)− (PerR, Mn) 211, 236, 256
    CcpCytochrome c peroxidaseNG1769P s (H2O2)+ (FNR/low O2 + OxyR, H2O2) 213, 239e
    MsrA/BMethionine sulfoxide reductaseNG2059C, OM s (H2O2, X/XO)+ (H2O2, Ecf σ factor) 221, 226f
    BfrABBacterioferritinNG0794, NG0795C s (H2O2, PQ)NA 49
    ScoPutative thiol:disulfide oxidoreductase/peroxiredoxinNG1237ND s (PQ)NA 211
    GSHGlutathione (GSH synthetase/glutamate-cysteine ligase)NG1217, NG0680CNANA 9
    GorGlutathione reductaseNG0925C x (H2O2)+ (OxyR, H2O2) 226 e
    PrxPeroxiredoxinNG0926C xx (H2O2)+ (OxyR)Seib et al., submitted
    LazAzurinNG0944OM s (H2O2)NA 255
    PriADNA replication restart helicaseNG1437C s (H2O2, CH)NA 142
    RecNDNA repairNG0318C s (H2O2)+ (H2O2) 226
    NG1686Putative zinc metalloproteaseNG1686ND s (H2O2, CH)+ (H2O2) 226
    NG0554 N. gonorrhoeae-specific predicted proteinNG0554ND s (H2O2)+ (H2O2) 226
Oxidative stress regulators
    OxyRH2O2-dependent regulatorNG1813C xx (X/XO, H2O2)KatA, Prx, Gor 235 e
    PerRMn-dependent repressorNG0542C xx (H2O2)MntABC, RpmEJ, AdhA 256
    FurFerric uptake regulation proteinNG1779CNAFur, SodB, BfrAB 23, 210
    FNRFumarate/nitrate reductase regulatorNG1579CNACcp 153, 239
    NmlR Neisseria merR-like regulatorNG0602C s (CH, diamide)AdhC, TrxB, CopA 34
  • a Annotation number from the N. gonorrhoeae FA 1090 genome on the Los Alamos National Laboratory website (http://www.stdgen.lanl.gov/stdgen/bacteria/ngon/index.html ), from the Gonococcal Genome Sequencing Project of the University of Oklahoma.

  • b C, cytoplasm; P, periplasm; IM, inner membrane; OM, outer membrane; ND, not determined.

  • c Sensitivity of mutant strains to in vitro oxidative stress killing assays relative to wild-type N. gonorrhoeae: x, same phenotype as the wild type; s, sensitive to killing; xx, resistant to killing (increased survival relative to the wild type). These assays typically involved exposure of a suspension of 104 to 106 cells over 1 h to either paraquat (PQ) (10 mM), xanthine (4.3 mM)/xanthine oxidase (300 mU/ml) (X/XO), or hydrogen peroxide (H2O2) (10 or 40 mM). Exposure to cumene hydroperoxide (CH) (0 to 1%) and diamide (0 to 50 mM) was performed with liquid cultures over 16 h. For further details, see the references cited in the table. NA, not available. PQ (PQ2+) (1,1′-4,4′-bipyridinium dichloride) is a redox compound that is reduced to the paraquat free radical (PQ·+) by low-potential electron donors within the bacterial cell. The paraquat free radical is then oxidized by dioxygen, leading to generation of the superoxide anion (O2·−). This redox cycling also depletes low-potential reducing agents within the cell, such as NADH (106).

  • d Regulation of defenses, either activated/upregulated (+) or repressed (−). Genes of interest, under the control of regulators, are also shown. For details, see the cited references. NA, not available.

  • e Also K. L. Seib, H. J. Wu, Y. N. Srikhanta, J. L. Edwards, T. L. Maguire, S. M. Grimmond, M. A. Apicella, A. G. McEwan, and M. P. Jennings, submitted for publication.

  • f Also J. K. Davies, personal communication.