Antibiotics have to penetrate the outer membrane to enter Gram-negative bacteria. One possible pathway is the diffusion through the lipid phase (Ribeiro et al., 2011), especially for the hydrophobic first-generation quinolones (Delcour, 2009). However, the outer membrane also contains a plethora of channel-forming pro teins called porins. Recent studies on multidrug resistance revealed modified...

Two porins, OmpK36 and OmpK35, have been described previously in Klebsiella pneumoniae, and they are homologous to the Escherichia coli porins OmpC and OmpF, respectively, at both the DNA and amino acid levels. Optimal resolution of the two K. pneumoniae porins by electrophoresis on polyacrylamide gels is not achieved using gel systems already described for E. coli and requires modifications of...

Several microbial components, such as bacterial DNA and flagellin, have been used as experimental vaccine adjuvants because of their inherent capacity to efficiently activate innate immune responses. Likewise, our previous work has shown that the major Salmonella Typhi (S. Typhi) outer membrane proteins OmpC and OmpF (porins) are highly immunogenic protective antigens that efficiently stimulate...

Resting B cells stimulated with dextran-conjugated anti-immunoglobulin D (anti-IgD) antibodies (anti-Ig-dex), a model for B-cell activation in response to polysaccharide antigens, proliferate but secrete little if any Ig, unless additional stimuli are present. In order to elucidate the parameters which costimulate T-cell-independent antipolysaccharide antibody responses during bacterial infecti...

Introduction Integral membrane protein structures constitute less than 2% of protein structures in the Protein Data Bank (PDB) (Bernstein et al., 1977). The known membrane protein structures can be divided into two structural classes: α helical and β stranded proteins. The β stranded membrane proteins form β barrel structures of which porins are type members. Porins are general diffusion, pore-...

The capability of Yersinia ruckeri to survive in the aquatic systems reflects its adaptation (most importantly through the alteration of membrane permeability) to the unfavorable environments. The nonspecific porins are a key factor contributing to the permeability. Here we studied the influence of the stimuli, such as temperature, osmolarity, and oxygen availability on regulation of Y. ruckeri...

The outer membrane of Gram-negative bacteria protects the cell against bactericidal substances. Passage of nutrients and waste is assured by outer membrane porins, beta-barrel transmembrane channels. While atomic structures of several porins have been solved, so far little is known on the supramolecular structure of the outer membrane. Here we present the first high-resolution view of a bacteri...

Due in large part to their ability to facilitate the diffusion of a diverse range of solutes across the outer membrane (OM) of Gram-negative bacteria, the porins represent one of the most prominent and important bacterial membrane protein superfamilies. Notably, for the Gram-negative bacterium Desulfovibrio vulgaris Hildenborough, a model organism for studies of sulfate-reducing bacteria, no ge...

In this study we examined the ability of Salmonella enterica serovar Typhimurium porins to activate activating protein 1 (AP-1) and nuclear factor kappaB (NF-kappaB) through the mitogen-activated protein kinase (MAPK) cascade, and we identified the AP-1-induced protein subunits. Our results demonstrate that these enzymes may participate in cell signaling pathways leading to AP-1 and NF-kappaB a...