β-Barrel assembly machinery protein A (BamA) plays a critical role in the biogenesis of outer membrane proteins (OMPs); however, a mechanistic understanding of its function is lacking. Here, we report an in vitro assay that investigates whether the mechanism of BamA-catalyzed OMP folding is stoichiometric or catalytic. We found that BamA accelerates the folding of OMPs in vitro via a catalytic ...

Although many periplasmic folding factors have been identified, the mechanisms by which they interact with unfolded outer membrane proteins (OMPs) to promote correct folding and membrane insertion remain poorly understood. Here, we have investigated the effect of two chaperones, Skp and SurA, on the folding kinetics of the OMP, PagP. Folding kinetics of PagP into both zwitterionic diC12:0PC (1,...

The outer membrane proteins (OMPs) of Branhamella catarrhalis were studied in an effort to identify surface-exposed determinants that are conserved among strains of the bacterium. Aliquots of polyclonal antiserum were absorbed individually by strains of B. catarrhalis. The absorbed antisera were tested in comparison with unabsorbed antiserum in an immunoblot assay against OMPs of the homologous...

The emergence of multiresistant Gram-negative bacteria requires new therapies for combating bacterial infections. Targeting the biogenesis of virulence factors could be an alternative strategy instead of killing bacteria with antibiotics. The outer membrane (OM) of Gram-negative bacteria acts as a physical barrier. At the same time it facilitates the exchange of molecules and harbors a multitud...

The bacterial envelope stress response (ESR) is triggered by the accumulation of misfolded outer membrane proteins (OMPs) upon envelope damage or excessive OMP synthesis, and is mediated by the alternative sigma factor, sigmaE. Activation of the GE pathway causes a rapid downregulation of major omp mRNAs, which prevents further build-up of unassembled OMPs and liberates the translocation and fo...

The Outer Membrane Protein (OMP) of Vibrio alginolyticus cell wall was administered intramuscularly (IM) to the tiger shrimp (Penaeus monodon Fab.) at 10, 20, 30 μg/kg bw. After 14 days infection, the tiger shrimps were challenged with 10(7) bacterial density of Vibrio harveyi for 24 hours. The total haemocyte count (THC), differential haemocyte count (DHC) and amount of total protein plasma (T...

A serotyping system for nontypable Haemophilus influenzae (NTHI) was developed by using isolated outer membrane protein (OMP) preparations and rabbit antisera. OMPs of 23 strains were isolated by molecular sieve chromatography of outer membranes in 1.5% sodium deoxycholate buffer. These OMP preparations were relatively free of lipopolysaccharide as determined by silver staining of sodium dodecy...

Different strains of Escherichia coli (E. coli) from human, chickens, and the common strain between human and chickens were isolated and typed with mono-specific antibody. The E. coli strains from each group of human, chicken and common between human and chicken were selected. The polypeptide patterns of selected strains were analyzed and compared with each other by Sodium dodecyle sulphate pol...

Like several other large, multimeric bacterial outer membrane proteins (OMPs), the assembly of the Klebsiella oxytoca OMP PulD does not rely on the universally conserved β-barrel assembly machinery (BAM) that catalyses outer membrane insertion. The only other factor known to interact with PulD prior to or during outer membrane targeting and assembly is the cognate chaperone PulS. Here, in vitro...

The outer membrane protein contents of Salmonella enterica serovar Typhimurium strains with PhoP/PhoQ regulon mutations were compared by two-dimensional gel electrophoresis. At least 26 species of outer membrane proteins (OMPs) were identified as being regulated by PhoP/PhoQ activation. One PhoP/PhoQ-activated OMP was identified by semiautomated tandem mass spectrometry coupled with electronic ...