BACKGROUND Construction of microbial biocatalysts for the production of biorenewables at economically viable yields and titers is frequently hampered by product toxicity. Membrane damage is often deemed as the principal mechanism of this toxicity, particularly in regards to decreased membrane integrity. Previous studies have attempted to engineer the membrane with the goal of increasing membran...

A hybrid gene consisting of the ompF promoter, the coding regions for the signal peptide, and the Ala-Glu residue of the OmpF NH2 terminus and the coding region for the major outer membrane lipoprotein devoid of the NH2-terminal cysteine residue was constructed. Escherichia coli carrying the cloned gene produced the predicted hybrid protein that is the same as the major lipoprotein except that ...

EnvZ, a histidine kinase/phosphatase in Escherichia coli, responds to the osmolarity changes in the medium by regulating the phosphorylation state of the transcription factor OmpR, which controls the expression levels of outer membrane porin proteins OmpF and OmpC. Although both ompR and envZ genes are located on the ompB locus under the control of the ompB promoter and transcribed as a single ...

The in vitro translocation of OmpF-Lpp, a model secretory protein, into inverted membrane vesicles of Escherichia coli obligatorily requires the proton motive force (delta mu H+) in the conventional assay system (Yamada, H., Tokuda, H., and Mizushima, S. (1989) J. Biol. Chem. 264, 1723-1728). The translocation, however, took place efficiently, even in the absence of delta mu H+, when the system...

Antibiotic resistant Gram-negative bacteria are a serious threat for public health. The permeation of antibiotics through their outer membrane is largely dependent on porin, changes in which cause reduced drug uptake and efficacy. Escherichia coli produces two major porins, OmpF and OmpC. MicF and MicC are small non-coding RNAs (sRNAs) that modulate the expression of OmpF and OmpC, respectively...

EnvZ and OmpR, the regulatory proteins for ompF and ompC expression in Escherichia coli, belong to a modulator-effector family of regulatory proteins which are essential for the response to environmental signals. We show that the soluble cytoplasmic domain of the transmembrane modulator protein EnvZ is phosphorylated in vitro by [gamma-32P]-ATP. We also demonstrate that the phosphate group can,...

A chromosomal gene of Enterobacter cloacae affecting the synthesis of major outer membrane proteins in E. cloacae and Escherichia coli was cloned by using selection for resistance to cefoxitin in E. coli. The presence of the gene, when plasmid-borne, led to a decrease in the amount of porin F in E. cloacae and the amount of OmpF in E. coli and caused 2- to 32-fold increases in the MICs of chlor...

Enzymatic colicins such as colicin E9 (ColE9) bind to BtuB on the cell surface of Escherichia coli and rapidly recruit a second coreceptor, either OmpF or OmpC, through which the N-terminal natively disordered region (NDR) of their translocation domain gains entry into the cell periplasm and interacts with TolB. Previously, we constructed an inactive disulfide-locked mutant ColE9 (ColE9(s-s)) t...

Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2 An oligonucleotide that encodes the N-terminal portion of a 41 kDa porin of Serratia marcescens was used to probe S. marcescens UOC-51 genomic DNA. An 11 kb EcoRl fragment which hybridized with the oligonucleotide was subcloned into Escherichia coli, examined for expression, and sequenced. The product express...

A novel mechanism of Escherichia coli porin regulation was discovered from multicopy suppressors that permitted growth of cells expressing a mutant OmpC protein in the absence of DegP. Analyses of two suppressors showed that both substantially lowered OmpC expression. Suppression activities were confined to a short DNA sequence, which we designated ipeX for inhibition of porin expression, and t...