Functional characterization of an isogenic meningococcal α-2,3-sialyltransferase mutant: the role of lipooligosaccharide sialylation for serum resistance in serogroup B meningococci

Vogel, Ulrich; Claus, Heike; Heinze, Gabriele; Frosch, Matthias

doi:10.1007/s004300050059

Cited by 32 publications

(46 citation statements)

References 19 publications

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“…With rare exceptions (33,34), almost all strains isolated from the blood or cerebrospinal fluid of infected patients possess a capsule. Capsular polysaccharide has also been shown to be necessary to cause invasive disease in the infant rat model (20,21). The mechanism of complement regulation by capsular polysaccharide has not been fully elucidated, but we suggest that capsular polysaccharide regulates the classical pathway by a mechanism that is independent of the binding of complement regulatory molecules (our unpublished observations).…”

Section: Discussionmentioning

confidence: 99%

“…Strains of N. meningitidis serogroups B, C, W-135, and Y can endogenously sialylate their LOS, and the shunting of sialic acid to LOS is facilitated in the siaD mutants (25). The ability of the siaD mutants to sialylate their LOS was abrogated by the introduction of a kanamycin resistance marker to inactivate the LOS sialyltransferase (lst) gene as described previously (20), to yield siaD lst double mutants. LOS sialylation of A2594 mynB or gonococcal strains was achieved by adding 5Ј-CMP-N-acetylneuraminic acid (CMP-NANA) to a final concentration of 50 g/ml in growth medium.…”

Section: Bacterial Strainsmentioning

confidence: 99%

“…In any event, meningococci that express the sialylated LNT LOS are recovered from the blood or cerebrospinal fluid of persons with invasive disease more frequently than isolates without LOS sialic acid (19), suggesting that LOS sialylation may be an important virulence factor. Nevertheless, serogroups B and C encapsulated meningococci genetically deficient in their ability to sialylate LOS have been found to be as virulent as wild-type strains in the infant rat model of meningococcal infection (20,21).…”

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confidence: 99%

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Factor H Binding and Function in Sialylated Pathogenic Neisseriae is Influenced by Gonococcal, but Not Meningococcal, Porin

Madico

Ngampasutadol

Gulati

et al. 2007

The Journal of Immunology

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Neisseria gonorrhoeae and Neisseria meningitidis both express the lacto-N-neotetraose (LNT) lipooligosaccharide (LOS) molecule that can be sialylated. Although gonococcal LNT LOS sialylation enhances binding of the alternative pathway complement inhibitor factor H and renders otherwise serum-sensitive bacteria resistant to complement-dependent killing, the role of LOS sialylation in meningococcal serum resistance is less clear. We show that only gonococcal, but not meningococcal, LNT LOS sialylation enhanced factor H binding. Replacing the porin (Por) B molecule of a meningococcal strain (LOS sialylated) that did not bind factor H with gonococcal Por1B augmented factor H binding. Capsule expression did not alter factor H binding to meningococci that express gonococcal Por. Conversely, replacing gonococcal Por1B with meningococcal PorB abrogated factor H binding despite LNT LOS sialylation. Gonococcal Por1B introduced in the background of an unsialylated meningococcus itself bound small amounts of factor H, suggesting a direct factor H-Por1B interaction. Factor H binding to unsialylated meningococci transfected with gonococcal Por1B was similar to the sialylated counterpart only in the presence of higher (20 μg/ml) concentrations of factor H and decreased in a dose-responsive manner by ∼80% at 1.25 μg/ml. Factor H binding to the sialylated strain remained unchanged over this factor H concentration range however, suggesting that LOS sialylation facilitated optimal factor H-Por1B interactions. The functional counterpart of factor H binding showed that sialylated meningococcal mutants that possessed gonococcal Por1B were resistant to complement-mediated killing by normal human serum. Our data highlight the different mechanisms used by these two related species to evade complement.

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Section: Discussionmentioning

confidence: 99%

Section: Bacterial Strainsmentioning

confidence: 99%

mentioning

confidence: 99%

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Factor H Binding and Function in Sialylated Pathogenic Neisseriae is Influenced by Gonococcal, but Not Meningococcal, Porin

Madico

Ngampasutadol

Gulati

et al. 2007

The Journal of Immunology

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“…For serogroup B N. meningitidis, the situation is different as the bacterium synthesizes sialic acid, which is incorporated into the capsule as well as LPS. Therefore, we investigated the contribution of sialic acid to fH binding to MC58 as this strain expresses a polysialic acid capsule and LPS immunotype (L3, L7, L9) that can be sialylated (39). The extent of fH binding was examined in strains lacking a capsule (MC58⌬siaD) or unable to synthesize sialic acid (MC58⌬siaC).…”

Section: The Interaction Between N Meningitidis and Fh Is Independenmentioning

confidence: 99%

Functional Significance of Factor H Binding toNeisseria meningitidis

Schneider

Exley

Chan

et al. 2006

The Journal of Immunology

219

197

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Neisseria meningitidis is an important cause of septicemia and meningitis. To cause disease, the bacterium must successfully survive in the bloodstream where it has to avoid being killed by host innate immune mechanisms, particularly the complement system. A number of pathogenic microbes bind factor H (fH), the negative regulator of the alternative pathway of complement activation, to promote their survival in vivo. In this study, we show that N. meningitidis binds fH to its surface. Binding to serogroups A, B, and C N. meningitidis strains was detected by FACS and Far Western blot analysis, and occurred in the absence of other serum factors such as C3b. Unlike Neisseria gonorrhoeae, binding of fH to N. meningitidis was independent of sialic acid on the bacterium, either as a component of its LPS or its capsule. Characterization of the major fH binding partner demonstrated that it is a 33-kDa protein; examination of insertion mutants showed that porins A and B, outer membrane porins expressed by N. meningitidis, do not contribute significantly to fH binding. We examined the physiological consequences of fH bound to the bacterial surface. We found that fH retains its activity as a cofactor of factor I when bound to the bacterium and contributes to the ability of N. meningitidis to avoid complement-mediated killing in the presence of human serum. Therefore, the recruitment of fH provides another mechanism by which this important human pathogen evades host innate immunity.

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“…Kahler et al (34) looked at mutants of an invasive serogroup B meningococcus with altered capsule, LPS, and sialylation; they stated that capsulation is essential for serum resistance but that LPS structures and sialylation also contribute. Vogel et al (70,71) studied isogenic ␣2-3 sialyltransferase (lst) mutants of three encapsulated clinical isolates. The mutants were more serum sensitive than the wild types, but only at high serum concentrations.…”

Section: The Effect Of Lactate Metabolism On Meningococcal Pathogenicitymentioning

confidence: 99%

Effect of Host Lactate on Gonococci and Meningococci: New Concepts on the Role of Metabolites in Pathogenicity

2007

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2In 1988, Britigan and colleagues (4) showed that the lactate in human neutrophils stimulated oxygen consumption by Neisseria gonorrhoeae and suggested that this might impair their oxygen-dependent bactericidal mechanisms. This first indication that lactate metabolism might be important in the pathogenicity of N. gonorrhoeae has been amply confirmed during the past decade (17,61,77), and now lactate has been shown to have important effects on Neisseria meningitidis (15,16). This review uses the work on gonococci as background to describe recent research on the meningococcus, which in turn provided the key to proving the influence of lactate on gonococcal pathogenicity in vivo. Studies on N. meningitidis showed that, in addition to a general stimulation of metabolism, lactate promotes the production of specific determinants of pathogenicity. Some differences between meningococci and gonococci in their responses to lactate are discussed, and new concepts of the role of metabolites in pathogenicity arising from the work are summarized. Throughout this review, it should be kept in mind that lactate is present in urogenital and respiratory secretions, blood, phagocytes, and cerebrospinal fluid (CSF), together with glucose and pyruvate (61), two other energy sources used effectively by gonococci and meningococci (37,42,43). Hence, in vivo, gonococci and meningococci grow on a mixture of carbon sources. To mimic this situation, most of the studies described deal with the influence of lactate on gonococci and meningococci growing in media containing glucose. STIMULATION OF GONOCOCCAL METABOLISM BY LACTATE: THE MECHANISM INVOLVED AND RELATION TO PATHOGENICITYThe original observations of the potential importance of lactate on the behavior of N. gonorrhoeae were reinforced by the demonstration that lactate in blood cell extracts enhanced the sialylation of gonococcal lipopolysaccharide (LPS) by cytidine-5Ј-monophospho-N-acetyl neuraminic acid (CMP-NANA) (49). Previous observations of gonococci harvested from urethral exudates had shown that host-derived CMP-NANA was incorporated into their LPS, rendering them resistant to killing by complement-mediated lysis in human serum, by phagocytes, and by antibody (24, 60). The enhancing effect of physiological concentrations of lactate on LPS sialylation occurred as gonococci were emerging from lag phase in a medium containing glucose. This resulted from an overall stimulation of metabolism, evidenced by greater LPS production (by 10 to 20%), enhanced protein synthesis (10 to 20%), and larger pentose contents (30 to 60%) (21, 22). Increased LPS sialylation occurs through greater production of both LPS and the sialyltransferase. There was more rapid emergence from lag phase with lactate and a 20% increase in the rate of logarithmic growth compared with glucose alone (22). Lactate was used more rapidly than glucose in a synthetic medium (22), as was seen in the fluid obtained from subcutaneous plastic chambers in guinea pigs that had been infected with gonococci (25).The mechanisms o...

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Functional characterization of an isogenic meningococcal α-2,3-sialyltransferase mutant: the role of lipooligosaccharide sialylation for serum resistance in serogroup B meningococci

Cited by 32 publications

References 19 publications

Factor H Binding and Function in Sialylated Pathogenic Neisseriae is Influenced by Gonococcal, but Not Meningococcal, Porin

Factor H Binding and Function in Sialylated Pathogenic Neisseriae is Influenced by Gonococcal, but Not Meningococcal, Porin

Functional Significance of Factor H Binding toNeisseria meningitidis

Effect of Host Lactate on Gonococci and Meningococci: New Concepts on the Role of Metabolites in Pathogenicity

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