Many Gram-negative bacteria, including human pathogens such as Pseudomonas aeruginosa, do not have large-channel porins. This results in an outer membrane (OM) that is highly impermeable to small polar molecules, making the bacteria intrinsically resistant towards many antibiotics. In such microorganisms, the majority of small molecules are taken up by members of the OprD outer membrane protein...

Disruption of the PA2491 gene in a mini-Tn5-tet insertion mutant of a clinical isolate of Pseudomonas aeruginosa increased expression of the mexEF-oprN multidrug efflux genes and decreased production of outer membrane protein OprD, concomitant with enhanced resistance to chloramphenicol, quinolones, and imipenem, which was reminiscent of previously described nfxC mutants. PA2491 encodes a proba...

The effects of imipenem and meropenem on the transcriptional expression of resistance-related genes oprD, oprM and oprN in Pseudomonas aeruginosa were studied by quantitative real-time PCR. Four strains were examined: the type strain PT5 (PAO1), its derivatives M7 and PT149, and a clinical isolate, PaKT3. The derivative M7 is a nalB mutant, overexpressing the MexAB-OprM pump, and the derivative...

The PhoE porin of Escherichia coli is induced by phosphate deprivation and when purified, forms moderately anion-selective channels in lipid bilayer membranes. To further investigate the basis of anion selectivity, PhoE was chemically acetylated with acetic anhydride. Acetylation modified the mobility and staining characteristics of the PhoE porin on SDS-polyacrylamide gel electrophoresis but t...

One potential vaccine strategy in the fight against meningococcal disease involves the exploitation of outer-membrane components of Neisseria lactamica, a commensal bacterium closely related to the meningococcus, Neisseria meningitidis. Although N. lactamica shares many surface structures with the meningococcus, little is known about the antigenic diversity of this commensal bacterium or the an...

Chemical modification of amino groups in matrix porin solubilized and purified from outer membranes of Escherichia coli in beta-octylglucoside was performed with eosin isothiocyanate and citraconic anhydride. At pH 7 8.5, the former reagent labeled a single amino group in the native protein, while more extensive derivatization was observed with increasing pH or upon denaturation. Citraconic anh...

conclusions the results of this study indicated that a decrease in oprd gene expression is an important mechanism of resistance in carbapenem resistant pseudomonas aeruginosa isolated from severe burn patients with secondary infection. results our study showed that 94.2% of the isolates were resistant to imipenem, 99.5% to meropenem, and all were resistant to ertapenem. the oprd gene expression...

Objectives To provide information about the genetic relationships and mechanism underlying carbapenem resistance in Pseudomonas aeruginosa clinical isolates of a hospital in China. Materials and methods One hundred and sixty P. aeruginosa strains were isolated from a hospital in China. Susceptibility to 14 antimicrobial agents was determined by antimicrobial susceptibility testing. Multilocus...

Mycobacteria have low-permeability outer membranes that render them resistant to most antibiotics. Hydrophilic nutrients can enter by way of transmembrane-channel proteins called porins. An x-ray analysis of the main porin from Mycobacterium smegmatis, MspA, revealed a homooctameric goblet-like conformation with a single central channel. This is the first structure of a mycobacterial outer-memb...