Purification and regulatory properties of MarA protein, a transcriptional activator of Escherichia coli multiple antibiotic and superoxide resistance promoters.
Expression of the marA or soxS genes is induced by exposure of Escherichia coli to salicylate or superoxides, respectively. This, in turn, enhances the expression of a common set of promoters (the mar/soxRS regulons), resulting in both multiple antibiotic and superoxide resistance. Since MarA protein is highly homologous to SoxS, and since a MalE-SoxS fusion protein has recently been shown to activate soxRS regulon transcription, the ability of MarA to activate transcription of these genes was tested. MarA was overexpressed as a histidine-tagged fusion protein, purified, cleaved with thrombin (leaving one N-terminal histidine residue), and renatured. Like MalE-SoxS, MarA (i) activated the transcription of zwf, fpr, fumC, micF, nfo, and sodA; (ii) required a 21-bp "soxbox" sequence to activate zwf transcription; and (iii) was "ambidextrous," i.e., required the C-terminal domain of the alpha subunit of RNA polymerase for activation of zwf but not fumC or micF. Thus, the mar and soxRS systems use activators with very similar specificities and mechanisms of action to respond to different environmental signals.
Department of Biological Sciences, University of Maryland Baltimore County 21228, USA.
K W
KW
Jair
R G
RG
Martin
J L
JL
Rosner
N
N
Fujita
A
A
Ishihama
R E
RE
Wolf
D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001483:Base Sequence; D004268:DNA-Binding Proteins; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D013481:Superoxides; D014157:Transcription Factors / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D015533:Transcriptional Activation
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C080002:MarA protein, E coli; D014157:Transcription Factors; D013481:Superoxides