Disease relevance of ompF

• Primary structure of the ompF gene that codes for a major outer membrane protein of Escherichia coli K-12 [1].
• 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 [2].
• The coa-test reagent consisted of Formalin-treated and heat-killed cells of Staphylococcus aureus, strain Cowan 1, sensitized with a high-titer rabbit anti-LT serum [3].

High impact information on ompF

• A naturally occurring small RNA molecule ( micF RNA), complementary to the region encompassing the Shine-Dalgarno sequence and initiation codon of the ompF mRNA, is known to block the expression of that mRNA in E. coli [4].
• A plasmid was constructed in which the structural gene for human beta-endorphin is preceded by the upstream region of the ompF gene consisting of the promoter region and the coding regions for the signal peptide and the N terminus of the OmpF protein [5].
• Phosphorylation of OmpR by the osmosensor EnvZ modulates expression of the ompF and ompC genes in Escherichia coli [6].
• Two different sequence motifs were found to be protected by OmpR in both the ompF and ompC promoter regions [7].
• Previously, the transfer of the phosphoryl group between the EnvZ and OmpR proteins, which are involved in activation of the ompF and ompC genes in response to the medium osmolarity, has been demonstrated in vitro [8].

Chemical compound and disease context of ompF

• Transfer of phosphoryl group between two regulatory proteins involved in osmoregulatory expression of the ompF and ompC genes in Escherichia coli [9].
• Salicylate inhibits the translation and transcription of ompF in Escherichia coli [10].

Biological context of ompF

• The promoter region and the transcription termination region of the ompF gene had a significantly high AT content, while the AT content of the coding region was about the same as the average AT content of the E. coli chromosome [1].
• The nucleotide sequence of the ompF gene coding for a major outer membrane protein of Escherichia coli K-12 has been determined and the amino acid sequence of the OmpF protein was deduced from it [1].
• Furthermore, we have determined that, although the OmpR activation site is not sufficient, OmpR is probably essential for ompF osmoregulation [11].
• Characterization of these deletion strains showed that both OmpR and EnvZ were necessary for transcription of ompF and ompC and that neither gene was essential for cell viability [12].
• SDS-PAGE analysis suggested that cell envelopes of staA or staA+ strains contained similar amounts of these proteins but characterization of strains carrying ompF (or C or A)-phoA gene fusions showed that mutation stA-2 reduced ompF gene expression by a factor of two [13].

Anatomical context of ompF

• EnvZ is a cytoplasmic membrane protein which is involved in osmoregulatory expression of the ompF and ompC genes in Escherichia coli possibly by sensing the environmental osmotic signal [9].
• Phosphorylation of OmpR, a transcription activator for ompF and ompC expression, is essential for its function and has been shown to be mediated in vitro by EnvZ, a transmembrane sensory receptor protein [14].
• The results of the coa-test and the CHO cell test correlated with 63 of 67 strains of human origin [3].

Associations of ompF with chemical compounds

• The phosphoryl group on EnvZ* could then be rapidly transferred to OmpR, which is a positive regulator of the ompF and ompC genes and which was proposed to interact with EnvZ in the process of osmoregulation [9].
• In vivo binding of the OmpR protein to the ompF and ompC promoter regions was observed using an in vivo dimethyl sulfate DNA footprinting technique [7].
• In this study, we used a combination of DNase I, dimethyl sulfate and hydroxyl radical footprinting analysis and DNA migration retardation assays to identify the bases within the ompF regulatory region that are in contact with OmpR [15].
• We also show that the soluble extracts from the envZ22(Am) strain grown in nutrient broth did not produce detectable bound forms of the ompF fragments, but low levels of DNA binding were detected with soluble extracts of the envZ22 strain grown in nutrient broth plus sucrose [16].
• When these aspartic acid residues were replaced with asparagine (D11N) or glutamine (D12Q and D55Q), ompF and ompC expression was almost completely blocked [14].

Regulatory relationships of ompF

• The ompF gene codes for a major outer membrane protein whose expression is positively regulated by the ompR and envZ genes [17].
• When micF was cloned into a high-copy-number plasmid it repressed ompF gene expression, whereas when cloned into a low-copy-number plasmid it did not [18].
• These results provide evidence that envZ function influences the DNA-binding activity of OmpR and suggest that high-affinity binding of OmpR to the upstream sequences of ompF is correlated with the repression of OmpF production [16].

Other interactions of ompF

• The two-component regulatory system, OmpR and EnvZ, in Escherichia coli controls the differential expression of ompF and ompC in response to medium osmolarity [19].
• We have constructed a series of ompF-lacZ fusions containing different regions of ompF to determine sites involved with osmoregulation [11].
• Surprisingly, the expression of ompF under the lpp promoter was still osmoregulated not only in the ompB+ strain but also in two ompB strains tested [20].
• The addition of the local anesthetic procaine to wild-type strains also causes a pleiotropic decrease in the expression of genes ompF, lamB, and phoA [21].
• The mutation leading to the loss of protein Ib in these strains is independent of the tolF mutation and is located near malP on the E. coli genetic map [22].

Analytical, diagnostic and therapeutic context of ompF

• Identification of the DNA-binding domain of the OmpR protein required for transcriptional activation of the ompF and ompC genes of Escherichia coli by in vivo DNA footprinting [7].
• Southern blot hybridization of V. cholerae genomic DNA digested with several restriction endonucleases with nick-translated E. coli ompF as the probe revealed no nucleotide sequence homology between the ompU and ompF genes [23].
• Six types of ompF mutation were found, including in-frame deletions and substitutions at Arg82 and Asp113, all affecting the channel constriction residues of OmpF [24].

References