|Synonyms: MprA, MprA-2,4-dinitrophenol, MprA-Carbonyl cyanide m-chlorophenylhydrazone (CCCP), MprA-Carbonyl cyanide p-(trifluoro-methoxy)phenylhydrazone|
The E. coli multidrug resistance regulator [2, 5], EmrR, negatively regulates the transcription of genes that code for multidrug resistance pumps that extrude structurally unrelated antimicrobial agents from the cell [2, 4] and possibly it also represses a gene that codes for a porin . When EmrR is overexpressed (the emrR gene in multicopy), it is able to repress the marRAB operon, which encodes two transcriptional regulators .
EmrR, which is also known as MprA, microcin production regulation, locus A , has also been shown to be a repressor of plasmid-encoded genes involved in microcin biosynthesis [7, 8, 9].
Microcins are low-molecular-weight polypeptide antibiotics .Read more >
The EmrR dimer binds 2,4-dinitrophenol, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and carbonyl cyanide p-(trifluoro-methoxy)phenylhydrazone, predicted ligands of the EmrAB pump, with high affinity . Binding of these agents interferes with the ability of EmrR to bind DNA . This dimeric protein  recognizes and binds an imperfect inverted repeat DNA sequence .
EmrR belongs to the MarR family of transcriptional regulators , which respond to a variety of phenolic compounds and are found in gram-positive and gram-negative species as well as in mycobacteria . The proteins of this family have a helix-turn-helix DNA-binding motif at the center , while the ligand-binding domain is possibly located at the N-terminal domain . EmrR shows 28% and 47% identity and similarity, respectively, to the MarR protein .
Overproduction of EmrR from a multicopy plasmid causes a mutator phenotype that includes an increase in frameshift and base substitution mutations .
emrR is the first gene of the emrRAB operon whose transcription is induced by antimicrobial agents such as salicylic acid, CCCP, and nalidixic acid, among others; induction requires the repressor of the operon EmrR . Expression of emrR is not osmoregulated .
Under oxidative stress conditions, translation of emrR is increased by the presence of polyamines. The increase is dependent on the suboptimal placement of the Shine-Dalgarno region upstream of the emrR open reading frame .
Reviews: [14, 15, 16]
|Connectivity class:||Local Regulator|
|Length:||531 bp / 176 aa|
|TU(s) encoding the TF:||
|Regulated gene(s)||acrA, acrB, emrA, emrB, mprA, nmpC|
|Multifun term(s) of regulated gene(s)||
MultiFun Term (List of genes associated to the multifun term)
drug resistance/sensitivity (5)
acrA, acrB, emrA, emrB, mprA
Porters (Uni-, Sym- and Antiporters) (4)
acrA, acrB, emrA, emrB
acrA, acrB, emrA, emrB
Transcription related (1)
mprARead more >
|Regulated operon(s)||acrAB, mprA-emrAB, nmpC|
|First gene in the operon(s)||acrA, mprA, nmpC|
|Simple and complex regulons|
|Simple and complex regulatory phrases||
Regulatory phrase (List of promoters regulated by the phrase)
|Functional conformation||Function||Promoter||Sigma factor||Central Rel-Pos||Distance to first Gene||Genes||Sequence||LeftPos||RightPos||Evidence (Confirmed, Strong, Weak)||References|
|MprA||repressor||mprAp||Sigma70||-10.0||-33.0||mprA, emrA, emrB||
|Evolutionary conservation of regulatory elements|
 Xiong A., Gottman A., Park C., Baetens M., Pandza S., Matin A., 2000, The EmrR protein represses the Escherichia coli emrRAB multidrug resistance operon by directly binding to its promoter region., Antimicrob Agents Chemother. 44(10):2905-7
 Rodionov DA., Gelfand MS., Mironov AA., Rakhmaninova AB., 2001, Comparative approach to analysis of regulation in complete genomes: multidrug resistance systems in gamma-proteobacteria., J Mol Microbiol Biotechnol. 3(2):319-24
 Sulavik MC., Gambino LF., Miller PF., 1995, The MarR repressor of the multiple antibiotic resistance (mar) operon in Escherichia coli: prototypic member of a family of bacterial regulatory proteins involved in sensing phenolic compounds., Mol Med. 1(4):436-46
 del Castillo I., Gomez JM., Moreno F., 1990, mprA, an Escherichia coli gene that reduces growth-phase-dependent synthesis of microcins B17 and C7 and blocks osmoinduction of proU when cloned on a high-copy-number plasmid., J Bacteriol. 172(1):437-45
 del Castillo I., Gonzalez-Pastor JE., San Millan JL., Moreno F., 1991, Nucleotide sequence of the Escherichia coli regulatory gene mprA and construction and characterization of mprA-deficient mutants., J Bacteriol. 173(12):3924-9
 Dalrymple BP., Swadling Y., 1997, Expression of a Butyrivibrio fibrisolvens E14 gene (cinB) encoding an enzyme with cinnamoyl ester hydrolase activity is negatively regulated by the product of an adjacent gene (cinR)., Microbiology. 143 ( Pt 4):1203-10
 Sakamoto A., Terui Y., Yoshida T., Yamamoto T., Suzuki H., Yamamoto K., Ishihama A., Igarashi K., Kashiwagi K., 2015, Three Members of Polyamine Modulon under Oxidative Stress Conditions: Two Transcription Factors (SoxR and EmrR) and a Glutathione Synthetic Enzyme (GshA)., PLoS One. 10(4):e0124883