Accession ARO:3000263
CARD Short NamemarA
DefinitionIn the presence of antibiotic stress, E. coli overexpresses the global activator protein MarA, which besides inducing MDR efflux pump AcrAB, also down- regulates synthesis of the porin OmpF.
AMR Gene Familyresistance-nodulation-cell division (RND) antibiotic efflux pump, General Bacterial Porin with reduced permeability to beta-lactams
Drug Classtetracycline antibiotic, penam, monobactam, rifamycin antibiotic, glycylcycline, cephalosporin, disinfecting agents and antiseptics, penem, cephamycin, carbapenem, phenicol antibiotic, fluoroquinolone antibiotic
Resistance Mechanismreduced permeability to antibiotic, antibiotic efflux
Efflux Componentefflux pump complex or subunit conferring antibiotic resistance
Efflux Regulatorprotein(s) and two-component regulatory system modulating antibiotic efflux
Resistomes with Perfect MatchesEscherichia colig+p+wgs, Klebsiella pneumoniaewgs, Shigella boydiig+wgs, Shigella dysenteriaeg+wgs, Shigella flexnerig+wgs, Shigella sonneig+wgs
Resistomes with Sequence VariantsCitrobacter amalonaticusg+wgs, Citrobacter freundiig+wgs, Citrobacter koserig+wgs, Citrobacter portucalensisg+wgs, Citrobacter werkmaniig+wgs, Citrobacter youngaeg+wgs, Cronobacter condimentig+wgs, Cronobacter dublinensisg+wgs, Cronobacter malonaticusg+wgs, Cronobacter sakazakiig+wgs, Cronobacter turicensiswgs, Cronobacter universalisg+wgs, Enterobacter asburiaeg+wgs, Enterobacter cancerogenusg+wgs, Enterobacter chengduensisg+wgs, Enterobacter cloacaeg+wgs, Enterobacter hormaecheig+p+wgs, Enterobacter kobeig+wgs, Enterobacter roggenkampiig+wgs, Escherichia albertiig+wgs, Escherichia colig+p+wgs, Escherichia fergusoniig+wgs, Escherichia marmotaeg+wgs, Klebsiella aerogenesg+wgs, Klebsiella huaxiensisg+wgs, Klebsiella michiganensisg+wgs, Klebsiella oxytocag+wgs, Klebsiella pneumoniaeg+p+wgs, Klebsiella quasipneumoniaeg+wgs, Kosakonia arachidisg+wgs, Leclercia adecarboxylatag+wgs, Raoultella planticolag+wgs, Salmonella bongorig+wgs, Salmonella entericag+wgs, Serratia marcescenswgs, Shigella boydiig+wgs, Shigella dysenteriaeg+wgs, Shigella flexnerig+wgs, Shigella sonneig+wgs
Classification32 ontology terms | Show
Parent Term(s)4 ontology terms | Show

Cohen SP, et al. 1988. J Bacteriol 170(12): 5416-5422. marA locus causes decreased expression of OmpF porin in multiple-antibiotic-resistant (Mar) mutants of Escherichia coli. (PMID 2848006)

Alekshun MN and Levy SB. 1997. Antimicrob Agents Chemother 41(10): 2067-2075. Regulation of chromosomally mediated multiple antibiotic resistance: the mar regulon. (PMID 9333027)

Randall LP and Woodward MJ. 2002. Res Vet Sci 72(2): 87-93. The multiple antibiotic resistance (mar) locus and its significance. (PMID 12027588)


Prevalence of marA among the sequenced genomes, plasmids, and whole-genome shotgun assemblies available at NCBI or IslandViewer for 413 important pathogens (see methodological details and complete list of analyzed pathogens). Values reflect percentage of genomes, plasmids, genome islands, or whole-genome shotgun assemblies that have at least one hit to the AMR detection model. Default view includes percentages calculated based on Perfect plus Strict RGI hits. Select the checkbox to view percentages based on only Perfect matches to AMR reference sequences curated in CARD (note: this excludes resistance via mutation as references in protein variant models are often wild-type, sensitive sequences).

Prevalence: protein homolog model (view sequences)

SpeciesNCBI ChromosomeNCBI PlasmidNCBI WGSNCBI GI
Citrobacter amalonaticus100%0%89.09%0%
Citrobacter freundii100%0%50.1%0%
Citrobacter koseri100%0%49.55%0%
Citrobacter portucalensis100%0%62.16%0%
Citrobacter werkmanii100%0%61.54%0%
Citrobacter youngae100%0%100%0%
Cronobacter condimenti100%0%100%0%
Cronobacter dublinensis100%0%100%0%
Cronobacter malonaticus100%0%85.45%0%
Cronobacter sakazakii100%0%92.15%0%
Cronobacter turicensis0%0%83.33%0%
Cronobacter universalis100%0%66.67%0%
Enterobacter asburiae100%0%70.75%0%
Enterobacter cancerogenus100%0%100%0%
Enterobacter chengduensis100%0%84%0%
Enterobacter cloacae98.21%0%73.16%0%
Enterobacter hormaechei98.56%0.06%66.9%0%
Enterobacter kobei100%0%68.12%0%
Enterobacter roggenkampii100%0%62.23%0%
Escherichia albertii94.29%0%59.35%0%
Escherichia coli67.68%0.06%61.52%0%
Escherichia fergusonii98.36%0%50%0%
Escherichia marmotae100%0%70.83%0%
Klebsiella aerogenes100%0%79.66%0%
Klebsiella huaxiensis100%0%66.67%0%
Klebsiella michiganensis100%0%68.88%0%
Klebsiella oxytoca100%0%74.37%0%
Klebsiella pneumoniae99.11%0.01%57.15%0%
Klebsiella quasipneumoniae99.16%0%73.29%0%
Kosakonia arachidis100%0%100%0%
Leclercia adecarboxylata100%0%60.47%0%
Raoultella planticola100%0%94.87%0%
Salmonella bongori100%0%94.74%0%
Salmonella enterica95.52%0%80.96%0%
Serratia marcescens0%0%0.13%0%
Shigella boydii93.33%0%94.44%0%
Shigella dysenteriae100%0%90%0%
Shigella flexneri99%0%81.21%0%
Shigella sonnei100%0%93.5%0%
Show Perfect Only

Detection Models

Model Type: protein homolog model

Model Definition: Protein Homolog Models (PHM) detect protein sequences based on their similarity to a curated reference sequence, using curated BLASTP bitscore cut-offs. Protein Homolog Models apply to all genes that confer resistance through their presence in an organism, such as the presence of a beta-lactamase gene on a plasmid. PHMs include a reference sequence and a bitscore cut-off for detection using BLASTP. A Perfect RGI match is 100% identical to the reference protein sequence along its entire length, a Strict RGI match is not identical but the bit-score of the matched sequence is greater than the curated BLASTP bit-score cutoff, Loose RGI matches have a bit-score less than the curated BLASTP bit-score cut-off.

Bit-score Cut-off (blastP): 230

>gb|BAA15221.2|+|marA [Escherichia coli str. K-12 substr. W3110]

>gb|AP009048.1|+|1621288-1621671|marA [Escherichia coli str. K-12 substr. W3110]