Heptose I Glycan Substitutions on<i>Neisseria gonorrhoeae</i>Lipooligosaccharide Influence C4b-Binding Protein Binding and Serum Resistance

Ram, Sanjay; Ngampasutadol, Jutamas; Cox, Andrew D.; Blom, Anna M.; Lewis, Lisa A.; Michael, Frank St.; Stupak, Jacek; Gulati, Sunita; Rice, Peter A.

doi:10.1128/iai.01109-06

Cited by 26 publications

(24 citation statements)

References 54 publications

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“…The ability of certain strains of gonococci (e.g., DGI isolates) to stably resist the bactericidal action of NHS has been linked, in part, to structural changes in the carbohydrate component of the core oligosaccharide of LOS (28,31,39,41,46). Phase-variable changes in the nucleotide repeat sequences within the lgtA and lgtC genes of the lgtABCDE operon (13) are important in determining resistance to killing by NHS expressed by strain FA19 (39).…”

Section: Resultsmentioning

confidence: 99%

Phosphoethanolamine Substitution of Lipid A and Resistance ofNeisseria gonorrhoeaeto Cationic Antimicrobial Peptides and Complement-Mediated Killing by Normal Human Serum

et al. 2009

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The capacity of Neisseria gonorrhoeae to cause disseminated gonococcal infection requires that such strains resist the bactericidal action of normal human serum. The bactericidal action of normal human serum against N. gonorrhoeae is mediated by the classical complement pathway through an antibody-dependent mechanism. The mechanism(s) by which certain strains of gonococci resist normal human serum is not fully understood, but alterations in lipooligosaccharide structure can affect such resistance. During an investigation of the biological significance of phosphoethanolamine extensions from lipooligosaccharide, we found that phosphoethanolamine substitutions from the heptose II group of the lipooligosaccharide ␤-chain did not impact levels of gonococcal (strain FA19) resistance to normal human serum or polymyxin B. However, loss of phosphoethanolamine substitution from the lipid A component of lipooligosaccharide, due to insertional inactivation of lptA, resulted in increased gonococcal susceptibility to polymyxin B, as reported previously for Neisseria meningitidis. In contrast to previous reports with N. meningitidis, loss of phosphoethanolamine attached to lipid A rendered strain FA19 susceptible to complement killing. Serum killing of the lptA mutant occurred through the classical complement pathway. Both serum and polymyxin B resistance as well as phosphoethanolamine decoration of lipid A were restored in the lptA-null mutant by complementation with wild-type lptA. Our results support a role for lipid A phosphoethanolamine substitutions in resistance of this strict human pathogen to innate host defenses.

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Section: Resultsmentioning

confidence: 99%

Phosphoethanolamine Substitution of Lipid A and Resistance ofNeisseria gonorrhoeaeto Cationic Antimicrobial Peptides and Complement-Mediated Killing by Normal Human Serum

et al. 2009

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“…The sensitivity of P5 mutants to serum was determined as previously described (52). Briefly, strains from log-phase cultures were diluted in Hanks' balanced salt solution (HBSS) with 0.15 mM calcium and 1 mM magnesium (HBSS ϩϩ ) to 1.3 ϫ 10 4 CFU/ml and incubated at 37°C for 30 min with or without pooled normal human serum (NHS) from healthy anonymous donors aged 18 to 65 years (final concentrations are specified in the figures) (Innovative Research, Novi, MI) and plated onto sBHI agar for CFU enumeration.…”

Section: Methodsmentioning

confidence: 99%

Outer Membrane Protein P5 Is Required for Resistance of Nontypeable Haemophilus influenzae to Both the Classical and Alternative Complement Pathways

2014

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The complement system is an important first line of defense against the human pathogen Haemophilus influenzae. To survive and propagate in vivo, H. influenzae has evolved mechanisms for subverting this host defense, most of which have been shown to involve outer surface structures, including lipooligosaccharide glycans and outer surface proteins. Bacterial defense against complement acts at multiple steps in the pathway by mechanisms that are not fully understood. Here we identify outer membrane protein P5 as an essential factor in serum resistance of both H. influenzae strain Rd and nontypeable H. influenzae (NTHi) clinical isolate NT127. P5 was essential for resistance of Rd and NT127 to complement in pooled human serum. Further investigation determined that P5 expression decreased cell surface binding of IgM, a potent activator of the classical pathway of complement, to both Rd and NT127. Additionally, P5 expression was required for NT127 to bind factor H (fH), an important inhibitor of alternative pathway (AP) activation. Collectively, the results obtained in this work highlight the ability of H. influenzae to utilize a single protein to perform multiple protective functions for evading host immunity.

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“…The sensitivity of dsbA mutants to serum was determined as previously described (57). Briefly, triplicate cultures of strains RXV, RdsbAV, RdsbAC, and RdgalU were grown as described above for the DTT sensitivity assay.…”

Section: Methodsmentioning

confidence: 99%

The Periplasmic Disulfide Oxidoreductase DsbA Contributes to Haemophilus influenzae Pathogenesis

2008

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Haemophilus influenzae is an obligate human pathogen that persistently colonizes the nasopharynx and causes disease when it invades the bloodstream, lungs, or middle ear. Proteins that mediate critical interactions with the host during invasive disease are likely to be secreted. Many secreted proteins require addition of disulfide bonds by the DsbA disulfide oxidoreductase for activity or stability. In this study, we evaluated the role in H. influenzae pathogenesis of DsbA, as well as HbpA, a substrate of DsbA. Mutants of H. influenzae Rd and type b strain Eagan having nonpolar deletions of dsbA were attenuated for bacteremia in animal models, and complemented strains exhibited virulence equivalent to that of the parental strains. Comparison of predicted secreted proteins in H. influenzae to known DsbA substrates in other species revealed several proteins that could contribute to the role of dsbA in virulence. One candidate, the heme transport protein, HbpA, was examined because of the importance of exogenous heme for aerobic growth of H. influenzae. The presence of a dsbA-dependent disulfide bond in HbpA was verified by an alkylation protection assay, and HbpA was less abundant in a dsbA mutant. The hbpA mutant exhibited reduced bacteremia in the mouse model, and complementation restored its in vivo phenotype to that of the parental strain. These results indicate that dsbA is required in vivo and that HbpA and additional DsbA-dependent factors are likely to participate in H. influenzae pathogenesis.Haemophilus influenzae efficiently colonizes the human nasopharyngeal mucosa in a primarily asymptomatic manner, and the carriage frequency is ϳ80% in healthy adults (48). However, it can disseminate to other anatomical sites and cause otitis media, upper and lower respiratory tract infections, septicemia, and meningitis in children (13,22,37,44,(48)(49)(50)63). The incidence of H. influenzae meningitis has dramatically declined in populations immunized with a vaccine against the type b capsular polysaccharide. The vaccine has not affected the incidence of infection with nontypeable H. influenzae (NTHi) strains, which lack the capsule. NTHi strains predominantly cause respiratory tract infections and otitis media but in rare cases can invade the bloodstream, leading to meningitis. This disease profile raises the possibility that genes promoting intravascular invasion could be present in NTHi strains (15,18,53,54). However, the molecular basis for the invasive properties of H. influenzae that promote transmission from the nasopharynx to the bloodstream or middle ear is not fully understood.Secreted bacterial proteins mediate critical aspects of pathogenesis, including attachment, nutrient utilization, and subversion of host defenses. Many secreted proteins of gram-negative bacteria acquire disulfide bonds in the periplasm that stabilize their mature, folded structures (9). Formation of such linkages has been most extensively studied in Escherichia coli, in which a series of disulfide oxidoreductases (Dsb) create and e...

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Heptose I Glycan Substitutions onNeisseria gonorrhoeaeLipooligosaccharide Influence C4b-Binding Protein Binding and Serum Resistance

Cited by 26 publications

References 54 publications

Phosphoethanolamine Substitution of Lipid A and Resistance ofNeisseria gonorrhoeaeto Cationic Antimicrobial Peptides and Complement-Mediated Killing by Normal Human Serum

Phosphoethanolamine Substitution of Lipid A and Resistance ofNeisseria gonorrhoeaeto Cationic Antimicrobial Peptides and Complement-Mediated Killing by Normal Human Serum

Outer Membrane Protein P5 Is Required for Resistance of Nontypeable Haemophilus influenzae to Both the Classical and Alternative Complement Pathways

The Periplasmic Disulfide Oxidoreductase DsbA Contributes to Haemophilus influenzae Pathogenesis

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