Disease relevance of ompR

• Osmoregulation of gene expression. I. DNA sequence of the ompR gene of the ompB operon of Escherichia coli and characterization of its gene product [1].
• Molecular analysis of the two-component genes, ompR and envZ, in the symbiotic bacterium Xenorhabdus nematophilus [2].
• Mutations in ompF and ompR genes affected production of an outer membrane porin protein, OmpF, and resulted in reduced sensitivity to a number of other agents (colicins, bacteriophages) besides microcin B17 [3].
• Although the order of the ompR and envZ genes of V. cholerae is similar to that of the ompB operon of E. coli, S. typhimurium and X. nematophilus, the Vibrio operon exhibits a number of novel features [4].
• Open reading frame 2 encodes a 26,000-dalton polypeptide that is similar to a family of transcriptional activators, including the products of the Bacillus subtilis spoOA and spoOF and the E. coli ompR and dye genes [5].

High impact information on ompR

• We purified the OmpR protein not only from wild-type cells but also from two ompR mutants (ompR2 and ompR3) exhibiting quite different phenotypes as to osmoregulation of the ompC and ompF genes [6].
• A second group of chemotactic revertants were mutated in the ompB gene region involved in osmoregulation, and they were still devoid of MDO [7].
• OmpR and EnvZ, the protein products of the ompB locus, are regulatory components required for osmoexpression of outer membrane porin proteins, OmpF and OmpC, in Escherichia coli [8].
• The molecular weight determined on sodium dodecyl sulfate-polyacrylamide gel, the total amino acid composition, and the NH2-terminal amino acid sequence of the purified protein were essentially the same as those deduced from the nucleotide sequence of the ompR gene [9].
• The OmpR protein has been purified to homogeneity from an overproducing strain harboring an ompR gene-carrying plasmid [9].

Biological context of ompR

• During our search of numerous bacteria we found that the symbiotic/pathogenic bacterium Xenorhabdus nematophilus contained the operon encoding both ompR and envZ [2].
• The sequence data also showed that ompR and envZ form an operon, where the coding regions overlap by four base-pairs [10].
• Isolation and characterization of delta ompB strains of Escherichia coli by a general method based on gene fusions [11].
• In the present work, five mutant ompR genes exhibiting different phenotypes of osmoregulation were cloned and sequenced [12].
• Cloning of the promoter region of ompB at a site 5' to the structural portion of the beta-galactosidase gene indicates that transcription of ompB is under positive control by cAMP [1].

Anatomical context of ompR

• To obtain direct evidence of its function in the adherence to and invasion of Vero cells, we generated Escherichia coli transformed by the vector pET-22b(+) inserted with the ompB open reading frame of R. japonica [13].

Associations of ompR with chemical compounds

• First, in a strain lacking ompR, the expression of flhDC is no longer responsive to a change in the level of acetyl phosphate [14].
• The loss of both OmpF and OmpC (ompR) reduced accumulation of norfloxacin, chloramphenicol, tetracycline, cephalothin and cefoxitin by 36-68% [15].
• Site-directed mutagenesis of the crp binding site provided evidence that this site is necessary for the in vivo regulation of ompB expression by cyclic AMP [16].

Regulatory relationships of ompR

• Expression of the ompF gene coding for a major outer membrane protein of Escherichia coli is positively regulated by the product of the ompR gene, OmpR [17].
• Expression of the ompC gene coding for a major outer-membrane protein of Escherichia coli is regulated by a transcriptional activation mechanism that requires the ompR gene product, OmpR [18].

Other interactions of ompR

• The published sequence of the ompR and envZ genes from Salmonella typhimurium is followed by a partial sequence that is highly homologous to pckA from E. coli [19].
• The promoter sequence of the ompC gene was compared with that of the ompF gene, both of which are controlled by the osmoregulatory operon, ompB [20].
• Similarly, induction of the dnaK:lacZ and ibp:lacZ fusions was not altered in either rpoS or ompR genetic backgrounds [21].
• The effect of SAL on ompF expression was independent of the osmolarity of the medium and was epistatic to certain ompB regulatory mutations: the high levels of ompF expression found in envZ3 and ompR472 strains were greatly reduced by growth in SAL [22].
• An attenuator precedes ecnA and an ompR-sensitive sigmaS promoter governs expression of ecnB [23].

Analytical, diagnostic and therapeutic context of ompR

• Scanning electron microscopy revealed that BPI treatment produced greater membrane perturbations in the ompR- strain, apparent even before lethal injury [24].
• Transcription levels of the two divergently transcribed agf operons required for biogenesis of thin aggregative fimbriae by Northern blot analysis with gene probes for agfA and agfD as well as expression levels of AgfA by Western blotting were compared in the wild type, the constitutive mutants and their respective ompR and rpoS- derivatives [25].
• The DNA corresponding to the open reading frame of the ompB gene of a spotted fever group rickettsia, Rickettsia japonica, was amplified by polymerase chain reaction [26].

Biochemical Parameters

• The binding affinity (K_d) of OmpR and OmpR-P for various pOmpC and pOmpF binding sites are summarized in Head, et al. [27] For example:
  • Binding to the pOmpF composite site F1-F2-F3, the OmpR-P K_d ≈ 15.4 ± 3.5 nM
  • Binding to the pOmpC composite site C1-C2-C3, the OmpR-P K_d ≈ 31.4 ± 8.0 nM

References