Outer membrane composition of a lipopolysaccharide-deficient Neisseria meningitidis mutant

Steeghs, Liana; Cock, Hans de; Evers, E.; Zomer, Bert; Tommassen, Jan; Ley, Peter van der

doi:10.1093/emboj/20.24.6937

Cited by 123 publications

(118 citation statements)

References 58 publications

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“…By electron microscopy, RBs in cells treated with LpxC inhibitors displayed normal outer and inner membranes, with no obvious differences in membrane thickness compared with untreated infected cells, as has been reported for N. meningitidis lpxA mutants (29). In these Neisseria mutants, the distribution of phosphatidylethanolamine and phosphatidylglycerol in inner and outer membranes was not affected, but their fatty acyl chains showed a shift toward shorter-chain saturated fatty acids (31). Future work will be aimed at determining if Chlamydia undergoes a similar adaptation upon treatment with LpxC inhibitors.…”

Section: Discussionsupporting

confidence: 69%

Lipooligosaccharide is required for the generation of infectious elementary bodies in Chlamydia trachomatis

Nguyen

Cunningham

Liang

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Lipopolysaccharides (LPS) and lipooligosaccharides (LOS) are the main lipid components of bacterial outer membranes and are essential for cell viability in most Gram-negative bacteria. Here we show that small molecule inhibitors of LpxC [UDP-3- O -( R -3-hydroxymyristoyl)-GlcNAc deacetylase], the enzyme that catalyzes the first committed step in the biosynthesis of lipid A, block the synthesis of LOS in the obligate intracellular bacterial pathogen Chlamydia trachomatis . In the absence of LOS, Chlamydia remains viable and establishes a pathogenic vacuole (“inclusion”) that supports robust bacterial replication. However, bacteria grown under these conditions were no longer infectious. In the presence of LpxC inhibitors, replicative reticulate bodies accumulated in enlarged inclusions but failed to express selected late-stage proteins and transition to elementary bodies, a Chlamydia developmental form that is required for invasion of mammalian cells. These findings suggest the presence of an outer membrane quality control system that regulates Chlamydia developmental transition to infectious elementary bodies and highlights the potential application of LpxC inhibitors as unique class of antichlamydial agents.

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Section: Discussionsupporting

confidence: 69%

Lipooligosaccharide is required for the generation of infectious elementary bodies in Chlamydia trachomatis

Nguyen

Cunningham

Liang

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…5B), indicating that the LPS produced in this strain was not accessible to PagL in the OM. Previously, it was reported that LPS depletion has no effect on assembly of OMPs in N. meningitidis (13), but to verify that the PagL produced in the imp mutant was functional, we determined PagL activity in membrane preparations. Cell envelopes containing or lacking PagL were incubated with purified LPS of the L3 immunotype and the modification of this LPS was assessed by Tricine-SDS͞ PAGE (Fig.…”

Section: Phenotype Of a Neisserial Imp Mutantmentioning

confidence: 99%

Identification of an outer membrane protein required for the transport of lipopolysaccharide to the bacterial cell surface

Bos

Tefsen

Geurtsen

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

231

226

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Lipopolysaccharide (LPS), also known as endotoxin due to its severe pathophysiological effects in infected subjects, is an essential component of the outer membrane (OM) of most Gramnegative bacteria. LPS is synthesized in the bacterial inner membrane, a process that is now well understood. In contrast, the mechanism of its transport to the outer leaflet of the OM has remained enigmatic. We demonstrate here that the OM protein, known as increased membrane permeability (Imp) or organic solvent tolerance protein, is involved in this process. An Impdeficient mutant of Neisseria meningitidis was viable and produced severely reduced amounts of LPS. The limited amount of LPS that was still produced was not accessible to LPS-modifying enzymes expressed in the OM or added to the extracellular medium. We conclude therefore that Imp mediates the transport of LPS to the cell surface. The role of Imp in LPS biogenesis and its high conservation among Gram-negative bacteria make it an excellent target for the development of novel antibacterial compounds. G ram-negative bacteria are enclosed by a cell envelope consisting of an inner membrane (IM) and an outer membrane (OM), separated by the periplasm. The IM is a phospholipid bilayer, whereas the OM is an asymmetrical bilayer, containing phospholipids in the inner leaflet and lipopolysaccharide (LPS) in the outer leaflet. LPS consists of a hydrophobic membrane anchor, lipid A, substituted with a nonrepeating oligosaccharide, the core region. In many bacteria, the core region is extended with the O antigen, a repeating oligosaccharide. The lipid A-core region and the O antigen are synthesized as separate units at the cytoplasmic leaflet of the IM. Almost all of the enzymes involved in their biosynthesis have been identified in Escherichia coli (1, 2). The transport of the lipid A-core moiety to the periplasmic side of the IM is mediated by the MsbA protein, an ATP-binding cassette family transporter (3), whereas flipping of O antigen units over the IM can be facilitated by several distinct mechanisms (1). At the periplasmic side of the IM, the O antigen is ligated to the lipid A-core region. The next step, transport of the fully assembled LPS through the periplasm and across the OM, remains an entirely elusive aspect of LPS biogenesis (1, 2). Recently, Omp85, an essential OMP, was suggested to be involved in this process (4). However, we found a severe OMP assembly defect in a Neisserial Omp85 mutant (5). This phenotype, together with the affinity of Omp85 for OMPs (5) and the presence of omp85 homologs in Gram-negative bacteria lacking LPS, are much more consistent with a role of this protein in OMP assembly, with only an indirect role in LPS transport. Braun and Silhavy (6) identified another essential OMP in E. coli, depletion of which resulted in the formation of aberrant membranes. Missense mutations in the gene encoding this 87-kDa OMP, called increased membrane permeability (Imp) or organic solvent tolerance protein, were already known to affect OM permeability (7,8). He...

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“…The capsular polysaccharide from serogroup B meningococci is an α-2,8-linked polysialic acid moiety mimetic of many human glycoproteins including the neural cell adhesion molecules (NCAM). As an alternative approach, outer membrane vesicles (OMV) vaccines depleted of lipooligosaccharide (LOS) to prevent local severe reactogenicity have been developed [4,5] and other protein vaccines containing overexpressed or tailored OMP(s) are under study but OMV vaccines devoid of endotoxin are poorly immunogenic [6].…”

Section: Introductionmentioning

confidence: 99%

TLR4-dependent adjuvant activity of Neisseria meningitidis lipid A

Zughaier

Steeghs

Ley³

et al. 2007

Vaccine

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The adjuvant activity of Neisseria meningitidis serogroup B lipopoly(oligo)saccharide (LOS) from wild-type and genetically-defined LOS mutants and unglycosylated meningococcal lipid A was assessed in C3H/HeN and C3H/HeJ mice. Meningococcal lipid A, a weak agonist for TLR4/MD-2 in human macrophages, was found to have adjuvant activity similar to that of wild-type and KDO 2 -lipid A LOS in C3H/HeN mice. All meningococcal LOS structures as adjuvants induced high titers of IgG1, IgG2a and IgG2b but very little IgG3 to OMP compared to no adjuvant PBS controls. In addition, induced OMP antibodies were shown to have high bactericidal activity against serogroup B meningococci. Purified LOS and lipid A structures failed to induce any adjuvant activity in C3H/ HeJ mice indicating that meningococcal LOS as an adjuvant was TLR4-dependent. Unglycosylated meningococcal lipid A because of its weak agonist activity for human macrophages and retention of adjuvant activity may be a candidate for use in serogroup B meningococcal OMP and OMV vaccines and for use as an adjuvant in other vaccines.

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Outer membrane composition of a lipopolysaccharide-deficient Neisseria meningitidis mutant

Cited by 123 publications

References 58 publications

Lipooligosaccharide is required for the generation of infectious elementary bodies in Chlamydia trachomatis

Lipooligosaccharide is required for the generation of infectious elementary bodies in Chlamydia trachomatis

Identification of an outer membrane protein required for the transport of lipopolysaccharide to the bacterial cell surface

TLR4-dependent adjuvant activity of Neisseria meningitidis lipid A

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