Disease relevance of micF

• Interaction of a redox-sensitive DNA-binding factor with the 5'-flanking region of the micF gene in Escherichia coli [1].
• DNA sequences from Salmonella typhi, Salmonella typhimurium, and Klebsiella pneumoniae show greater than 96% homology in the micF gene when compared to the Escherichia coli micF sequence [2].
• Southern analyses show that the micF gene is present in related Gram-negative bacteria, including Salmonella typhimurium, Klebsiella pneumoniae, and Pseudomonas aeruginosa [2].
• The regulatory RNA gene micF is present in several species of gram-negative bacteria and is phylogenetically conserved [2].

High impact information on micF

• While the complete absence of HU does not abolish the osmoregulation of OmpF protein synthesis, the steady-state level of micF RNA, the negative regulator of OmpF, decreases in bacteria lacking HU, increasing the basal level of this membrane protein [3].
• The binding sites of SoxS in the zwf and micF promoters were identified by DNase I footprinting, which revealed an extended protected region immediately upstream of the respective -35 sites [4].
• Levels of micF RNA as determined by Northern analyses are found to increase in response to cell growth at high temperature, in high osmolarity or in the presence of ethanol [5].
• In addition, while levels of ompF mRNA are substantially reduced in both strains in response to high osmolarity or ethanol at 24 degrees C, the reduced levels in the parental strain are still 4-5-fold lower compared with the micF deletion strain [5].
• A role for the Escherichia coli H-NS-like protein StpA in OmpF porin expression through modulation of micF RNA stability [6].

Biological context of micF

• We report here that two DNA-binding factors compete for the same site in the promoter region of the micF gene: RSBF, a high-affinity redox-sensitive DNA-binding factor that responds to an active oxygen species other than hydrogen peroxide or superoxide anions; and HRBF a heat-resistant DNA-binding factor [1].
• Both RSBF and HRBF bind to the same DNA sequence, 5'-TTAAAATCAATAACTTATTCTTAA3-', located upstream of the transcription start site of the micF gene [1].
• In E. coli, a decrease in OmpF seemed to be linked to the activation of the micF operon in most of the mutants described [7].
• Furthermore, we establish that the antibiotic resistance phenotype is primarily due to the induction of the MarRAB regulatory system by the AOAs, while other regulatory pathways that also converge into micF modulation (OmpR/EnvZ, SoxRS, and Lrp) remained unaltered [8].
• Both in wild-type and mar-deficient strains, growth in salicylate resulted in increased antibiotic resistance, decreased permeation of the outer membrane to cephaloridine, increased micF transcription, and decreased amounts of OmpF [9].

Associations of micF with chemical compounds

• Methylation interference identified several conserved purine residues required for binding to micF and five other SoxS-binding sites [10].

Other interactions of micF

• micF RNA is a substrate for RNase E [11].

Analytical, diagnostic and therapeutic context of micF

• RobA from E. cloacae was found to inhibit ompF expression at the posttranscriptional level via activation of micF, a gene also apparently present in E. cloacae, as detected by PCR [12].
• This reduction was mostly restored by a micF null mutation, and the micF RNA that inhibits the ompF mRNA translation was present 1.3 to 1.4 times more in the pgsA3 mutant, as assayed by RNase protection and Northern blot analyses [13].

References