A. Multiply antibiotic resistant bacteria are an increasingly important problem in the treatment of infectious disease. In Escherichia coli and other enteric bacteria, expression of the marRAB operon confers resistance to a variety of antibiotics and superoxide- generating agents. We previously purified MarR, the repressor of the operon, described its binding to the mar promoter and the reduction of this DNA binding when MarR is bound by salicylate, an inducer of the operon. We have also purified the MarA product and have shown that it is a transcriptional activator for a number of genes of the mar regulon in vitro. We have now begun a systematic analysis of the mar promoter by synthesizing (24) 5 base-pair (bp) transversion mutations that span 120 bp of the promoter. This has allowed us to identify: the putative -35 and -10 RNA polymerase sigma 70 recognition hexamers; the site of MarA binding; the requirement for proper phasing between the MarA site and the -35 hexamer; and a new site which binds Fis (a small DNA-binding and -bending protein). Furthermore, we have demonstrated roles for Rob and SoxS, two MarA-like transcriptional activators, and for Fis in activating the mar operon in vivo. The ability to bind these activators presumably attunes the operon to diverse internal and external stimuli. B. We previously demonstrated that isoniazid (INH), a clinically important antituberculosis drug, induced an SOS-like response and lethality in peroxidase mutants of E.coli and Salmonella typhimurium. We are now isolating and sequencing INH-resistant mutants of these strains to help elucidate this mechanism of INH action.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Intramural Research (Z01)
Project #
1Z01DK036003-12
Application #
2573109
Study Section
Special Emphasis Panel (LMB)
Project Start
Project End
Budget Start
Budget End
Support Year
12
Fiscal Year
1996
Total Cost
Indirect Cost
City
State
Country
United States
Zip Code
Rosner, Judah L; Martin, Robert G (2009) An excretory function for the Escherichia coli outer membrane pore TolC: upregulation of marA and soxS transcription and Rob activity due to metabolites accumulated in tolC mutants. J Bacteriol 191:5283-92
Zhang, Aixia; Rosner, Judah L; Martin, Robert G (2008) Transcriptional activation by MarA, SoxS and Rob of two tolC promoters using one binding site: a complex promoter configuration for tolC in Escherichia coli. Mol Microbiol 69:1450-5
Martin, Robert G; Bartlett, Emily S; Rosner, Judah L et al. (2008) Activation of the Escherichia coli marA/soxS/rob regulon in response to transcriptional activator concentration. J Mol Biol 380:278-84
Kawano, Mitsuoki; Storz, Gisela; Rao, B Sridhar et al. (2005) Detection of low-level promoter activity within open reading frame sequences of Escherichia coli. Nucleic Acids Res 33:6268-76
Martin, Robert G; Rosner, Judah L (2004) Transcriptional and translational regulation of the marRAB multiple antibiotic resistance operon in Escherichia coli. Mol Microbiol 53:183-91
Dangi, Bindi; Gronenborn, Angela M; Rosner, Judah L et al. (2004) Versatility of the carboxy-terminal domain of the alpha subunit of RNA polymerase in transcriptional activation: use of the DNA contact site as a protein contact site for MarA. Mol Microbiol 54:45-59
Thomason, Lynn C; Court, Donald L; Datta, Atin R et al. (2004) Identification of the Escherichia coli K-12 ybhE gene as pgl, encoding 6-phosphogluconolactonase. J Bacteriol 186:8248-53
Martin, Robert G; Rosner, Judah L (2003) Analysis of microarray data for the marA, soxS, and rob regulons of Escherichia coli. Methods Enzymol 370:278-80
Rosner, Judah L; Dangi, Bindi; Gronenborn, Angela M et al. (2002) Posttranscriptional activation of the transcriptional activator Rob by dipyridyl in Escherichia coli. J Bacteriol 184:1407-16
Martin, Robert G; Gillette, William K; Martin, Nicholas I et al. (2002) Complex formation between activator and RNA polymerase as the basis for transcriptional activation by MarA and SoxS in Escherichia coli. Mol Microbiol 43:355-70

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