The Omp85 protein of Neisseria meningitidis is required for lipid export to the outer membrane

Genevrois, Stéphanie; Steeghs, Liana; Roholl, P. J. M.; Letesson, Jean‐Jacques; Ley, Peter van der

doi:10.1093/emboj/cdg174

Cited by 107 publications

(90 citation statements)

References 50 publications

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“…Previously, another essential OMP, Omp85, has been suggested to be involved in LPS transport (4). However, we have demonstrated a strong OMP assembly defect in an Omp85-depleted strain (5).…”

Section: Discussionmentioning

confidence: 62%

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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.

235

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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Section: Discussionmentioning

confidence: 62%

“…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).…”

mentioning

confidence: 52%

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.

235

226

View full text Add to dashboard Cite

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“…Immunofluoresence microscopy on knockout Neisseria strains has illustrated the importance of Omp85, as the binding of antibodies directed against a number of OMPs (PilQ, PorA, and PorB) was considerably weaker than wild types. Further, electron-dense material accumulates in the periplasm of Neisseria Omp85-depleted strains, and although the identity of this material could not be revealed (Genevrois et al 2003), it is most likely misassembled OMPs (Voulhoux and Tommassen 2004). The fact that Omp85 is also located in the lipopolysaccharide biosynthetic operon (Genevrois et al 2003;Voulhoux et al 2003) reinforces the view that this gene has an important role in OMP biogenesis.…”

Section: Introductionmentioning

confidence: 91%

“…Omp85 homologues have been shown to be present in all gram-negative bacteria (Genevrois et al 2003;Gentle et al 2004;Stephens and Lammel 2001;Voulhoux and Tommassen 2004) and also eukaryote mitochondria, where they are involved in mitochondrial biogenesis. Omp85 can be divided into two domains, a periplasmic NH 2 -terminal domain and a 12-stranded b-barrel domain at the COOH-terminus (Voulhoux et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Evidence of Positive Darwinian Selection in Omp85, a Highly ConservedBacterial Outer Membrane Protein Essential for Cell Viability

Fitzpatrick

McInerney

2005

J Mol Evol

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Abstract. Omp85 is a highly conserved outer membrane protein found in all gram-negative bacteria. It is essential for bacterial cell viability and plays an integral function in the positioning and folding of other outer membrane proteins into the bacterial outer membrane. We have employed a maximum likelihood and a maximum parsimony approach to detect evidence of positive Darwinian selection in Omp85 homologues from 10 d-proteobacteria and have identified 14 amino acid sites that show evidence of being under the influence of adaptive evolution. Interestingly all sites bar one are concentrated within surface loops of the protein that most likely interact with host immune response or the surrounding environment. Alternatively amino acids within membrane-spanning regions of the protein are found to be under purifying selection most likely as a result of structural constraints.

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“…Members of this family are present in diverse organisms across the evolutionary spectrum, including bacteria, fungi, plants, and animals (1, 4). The widespread nature of Omp85-like proteins underscores their critical role in cellular processes, highlighted by the fact that many are required for cell viability (3,4,(6)(7)(8)(9). Although all Omp85-like proteins share sequence homology, they can be grouped into two classes based on the specific role that they play in protein translocation.…”

mentioning

confidence: 99%

Evidence for conservation of architecture and physical properties of Omp85-like proteins throughout evolution

Surana

Grass

Hardy

et al. 2004

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

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Omp85-like proteins represent a family of proteins involved in protein translocation, and they are present in all domains of life, except archaea. In eukaryotes, Omp85-like proteins have been demonstrated to form tetrameric pore-forming complexes that interact directly with their substrate proteins. Studies performed with bacterial Omp85-like proteins have demonstrated pore-forming activity but no evidence of multimerization. In this article, we characterize the Haemophilus influenzae HMW1B protein, an Omp85-like protein that has been demonstrated to be critical for secretion of the H. influenzae HMW1 adhesin. Analysis of purified protein by biochemical and electron microscopic techniques revealed that HMW1B forms a tetramer. Examination using liposomeswelling assays demonstrated that HMW1B has pore-forming activity, with a pore size of Ϸ2.7 nm. Far-Western blot analysis established that HMW1B interacts with the N terminus of HMW1. These results provide evidence that a bacterial Omp85-like protein forms a tetramer and interacts directly with a substrate protein, suggesting that the architecture and physical properties of Omp85-like proteins have been conserved throughout evolution. O mp85-like proteins represent a large family defined by phylogenetic relatedness, secondary-structure predictions, and a role in protein translocation (1-5). Members of this family are present in diverse organisms across the evolutionary spectrum, including bacteria, fungi, plants, and animals (1, 4). The widespread nature of Omp85-like proteins underscores their critical role in cellular processes, highlighted by the fact that many are required for cell viability (3,4,(6)(7)(8)(9). Although all Omp85-like proteins share sequence homology, they can be grouped into two classes based on the specific role that they play in protein translocation. One class is typified by Saccharomyces cerevisiae Sam50 and Neurospora crassa Tob55, which are chiefly involved in insertion of ␤-barrel proteins into the outer membrane (OM) of mitochondria (6, 9). The second class is epitomized by the chloroplast protein Toc75, which is involved in secretion of proteins across a membrane (10, 11). Interestingly, both classes of Omp85-like proteins are present in Gramnegative bacteria. Neisseria meningitidis Omp85, the namesake of this family of proteins, has been demonstrated recently to be critical for the insertion of proteins into the bacterial OM (7). Other Gram-negative bacterial Omp85-like proteins, including Serratia marcescens ShlB and Bordetella pertussis FhaC [and other members of the so-called two-partner secretion (TPS) pathway], have been demonstrated to function in protein export across the OM (12).The high level of amino acid homology among Omp85-like proteins from bacteria to humans raises the possibility that members of this family have similar structures. Although no crystal structures exist so far for Omp85-like proteins, several of these proteins have been subjected to biochemical studies of overall architecture. In eukaryotes, both classes...

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The Omp85 protein of Neisseria meningitidis is required for lipid export to the outer membrane

Cited by 107 publications

References 50 publications

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

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

Evidence of Positive Darwinian Selection in Omp85, a Highly ConservedBacterial Outer Membrane Protein Essential for Cell Viability

Evidence for conservation of architecture and physical properties of Omp85-like proteins throughout evolution

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