Conformation of Escherichia coli outer membrane protein OmpA produced in Bacillus subtilis: Influence of lipopolysaccharide

Puohiniemi, R

doi:10.1016/0378-1097(93)90063-8

Cited by 1 publication

(1 citation statement)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…MLP and PAL are lipoproteins with covalently attached lipids. The OMPs are tightly associated with LPS (37,53). OmpA, PAL, and MLP have not been studied extensively in the context of gram-negative sepsis, although it has been known for several decades that many proteins associated with LPS are biologically active (14,19,21,22,24,25,28,38,40,41,44,51,67).…”

Section: Discussionmentioning

confidence: 99%

Outer Membrane Protein A, Peptidoglycan-Associated Lipoprotein, and Murein Lipoprotein Are Released byEscherichia coliBacteria into Serum

Hellman

Loiselle²,

Tehan

et al. 2000

Infect Immun

View full text Add to dashboard Cite

4Complexes containing lipopolysaccharide (LPS) and three outer membrane proteins (OMPs) are released by gram-negative bacteria incubated in human serum and into the circulation in an experimental model of sepsis. The same OMPs are bound by immunoglobulin G (IgG) in the cross-protective antiserum raised to Escherichia coli J5 (anti-J5 IgG). This study was performed to identify the three OMPs. The 35-kDa OMP was identified as outer membrane protein A (OmpA) by immunoblotting studies using OmpA-deficient bacteria and recombinant OmpA protein. The 18-kDa OMP was identified as peptidoglycan-associated lipoprotein (PAL) based on peptide sequences from the purified protein and immunoblotting studies using PAL-deficient bacteria. The 5-to 9-kDa OMP was identified as murein lipoprotein (MLP) based on immunoblotting studies using MLPdeficient bacteria. The studies identify the OMPs released into human serum and into the circulation in an experimental model of sepsis as OmpA, PAL, and MLP.Bacterial cell wall components released into the bloodstream are believed to be important in the pathogenesis of gram-negative sepsis. Although prior investigators have reported that bacteria release lipopolysaccharide (LPS) into serum (62, 63) and into the circulation (4,18,56,66), the full composition of released bacterial products has not been established. Very little is known about release of non-LPS gramnegative outer membrane components such as outer membrane proteins (OMPs) in sepsis. Fragments containing LPS, OmpA, and another faintly staining protein, of 17 kDa, were affinity purified from filtrates of human serum incubated with Salmonella enterica serovar Abortus equi bacteria using Ochain-specific anti-LPS immunoglobulin G (IgG) (20). Similarly, we have affinity purified complexes containing LPS and at least three OMPs, with estimated molecular masses of 35, 18, and 5 to 9 kDa, from filtrates of normal human serum incubated with Escherichia coli bacteria, using O-chain-specific anti-LPS IgG (29,30).Previous studies indicated that passive and active immunity directed to rough mutant bacteria such as S. enterica serovar Minnesota Re595 and E. coli J5 protect in experimental and clinical gram-negative sepsis (1,5,11,42,43,68). Protection has been attributed to antibodies directed to conserved core components of LPS (lipid A and core oligosaccharide). However, it has been difficult to prove that antisera to rough strains of bacteria contain cross-reactive anti-lipid A or anti-core oligosaccharide IgGs (15, 57), and the exact mechanism of protection remains unclear and controversial.We have demonstrated that IgG in antiserum raised to heatkilled E. coli J5 (J5 antiserum) binds to the same three gramnegative bacterial OMPs that are released into serum in the OMP-LPS complexes described above (30). OMP-LPS complexes are also released into the bloodstream of burned rats with E. coli O18K ϩ sepsis (29). In addition, at least one OMP, with an estimated molecular mass of 18 kDa, is released from bacteria separately from the OMP-LPS comple...

show abstract