Skip to main content
PMC home page
Journal of Bacteriology logoLink to Journal of Bacteriology
. 1993 Mar;175(5):1484–1492. doi: 10.1128/jb.175.5.1484-1492.1993

Genetic and functional analysis of the multiple antibiotic resistance (mar) locus in Escherichia coli.

S P Cohen 1, H Hächler 1, S B Levy 1
PMCID: PMC193236  PMID: 8383113

Abstract

A 7.8-kbp fragment of chromosomal DNA from a region controlling multiple antibiotic resistance (Mar) in Escherichia coli has been sequenced. Within the fragment is a potential divergent promoter region including marO, which contains two pairs of direct repeats, suggesting possible operator-regulatory sites. To the left of marO (region I) are one or two transcriptional units with three putative open reading frames (ORFs) encoding 64, 157, and 70 amino acids. To the right (region II) is a transcriptional unit containing three putative ORFs (ORF125/144, ORF129, and ORF72). Of six independent Mar mutants, four had mutations within the ORF encoding the first putative protein (ORF125/144) downstream of marO, including three different single-point mutations and an IS2 insertion. One of the other mutations occurred in marO (20-bp duplication), and the other occurred in a site in marO or ORF144 (a 1-bp change). All six mutations led to increased transcription of the region II transcript. High-copy-number plasmids containing marO and the adjacent ORF125/144 region from a wild-type source but not from a Mar mutant reduced the antibiotic resistance of a Mar mutant to levels comparable to those of wild-type cells. High-copy-number plasmids containing wild-type marO alone caused an increase in resistance to tetracycline, chloramphenicol, and norfloxacin in a wild-type strain. The nature of the Mar mutations and the results of the complementation studies suggest that ORF125/144 encodes a repressor (designated MarR) which acts at marO. The second ORF (ORF129), designated marA, would encode a protein, MarA, whose sequence shows strong similarity to those of a family of positive transcriptional regulators. A Tn5 insertion in marA inactivated the multiresistance phenotype of Mar mutants. The function of ORF72, designated marB, encoding the third putative protein in the operon, and that of other ORFs detected within the 7.8-kb fragment have not yet been determined.

Full text

PDF
1484

Images in this article

1489Image
on p.1489

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Amábile-Cuevas C. F., Demple B. Molecular characterization of the soxRS genes of Escherichia coli: two genes control a superoxide stress regulon. Nucleic Acids Res. 1991 Aug 25;19(16):4479–4484. doi: 10.1093/nar/19.16.4479. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Becker S., Plapp R. Location of the dcp gene on the physical map of Escherichia coli. J Bacteriol. 1992 Mar;174(5):1698–1699. doi: 10.1128/jb.174.5.1698-1699.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Brutlag D. L., Dautricourt J. P., Maulik S., Relph J. Improved sensitivity of biological sequence database searches. Comput Appl Biosci. 1990 Jul;6(3):237–245. doi: 10.1093/bioinformatics/6.3.237. [DOI] [PubMed] [Google Scholar]
  4. Chou P. Y., Fasman G. D. Conformational parameters for amino acids in helical, beta-sheet, and random coil regions calculated from proteins. Biochemistry. 1974 Jan 15;13(2):211–222. doi: 10.1021/bi00699a001. [DOI] [PubMed] [Google Scholar]
  5. Cohen S. P., McMurry L. M., Hooper D. C., Wolfson J. S., Levy S. B. Cross-resistance to fluoroquinolones in multiple-antibiotic-resistant (Mar) Escherichia coli selected by tetracycline or chloramphenicol: decreased drug accumulation associated with membrane changes in addition to OmpF reduction. Antimicrob Agents Chemother. 1989 Aug;33(8):1318–1325. doi: 10.1128/aac.33.8.1318. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Cohen S. P., McMurry L. M., Levy S. B. marA locus causes decreased expression of OmpF porin in multiple-antibiotic-resistant (Mar) mutants of Escherichia coli. J Bacteriol. 1988 Dec;170(12):5416–5422. doi: 10.1128/jb.170.12.5416-5422.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Curiale M. S., Levy S. B. Two complementation groups mediate tetracycline resistance determined by Tn10. J Bacteriol. 1982 Jul;151(1):209–215. doi: 10.1128/jb.151.1.209-215.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. George A. M., Levy S. B. Amplifiable resistance to tetracycline, chloramphenicol, and other antibiotics in Escherichia coli: involvement of a non-plasmid-determined efflux of tetracycline. J Bacteriol. 1983 Aug;155(2):531–540. doi: 10.1128/jb.155.2.531-540.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. George A. M., Levy S. B. Gene in the major cotransduction gap of the Escherichia coli K-12 linkage map required for the expression of chromosomal resistance to tetracycline and other antibiotics. J Bacteriol. 1983 Aug;155(2):541–548. doi: 10.1128/jb.155.2.541-548.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Glansdorff N., Charlier D., Zafarullah M. Activation of gene expression by IS2 and IS3. Cold Spring Harb Symp Quant Biol. 1981;45(Pt 1):153–156. doi: 10.1101/sqb.1981.045.01.024. [DOI] [PubMed] [Google Scholar]
  11. Greenberg J. T., Chou J. H., Monach P. A., Demple B. Activation of oxidative stress genes by mutations at the soxQ/cfxB/marA locus of Escherichia coli. J Bacteriol. 1991 Jul;173(14):4433–4439. doi: 10.1128/jb.173.14.4433-4439.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Gutmann L., Williamson R., Moreau N., Kitzis M. D., Collatz E., Acar J. F., Goldstein F. W. Cross-resistance to nalidixic acid, trimethoprim, and chloramphenicol associated with alterations in outer membrane proteins of Klebsiella, Enterobacter, and Serratia. J Infect Dis. 1985 Mar;151(3):501–507. doi: 10.1093/infdis/151.3.501. [DOI] [PubMed] [Google Scholar]
  13. Hashimoto-Gotoh T., Franklin F. C., Nordheim A., Timmis K. N. Specific-purpose plasmid cloning vectors. I. Low copy number, temperature-sensitive, mobilization-defective pSC101-derived containment vectors. Gene. 1981 Dec;16(1-3):227–235. doi: 10.1016/0378-1119(81)90079-2. [DOI] [PubMed] [Google Scholar]
  14. Hirai K., Aoyama H., Suzue S., Irikura T., Iyobe S., Mitsuhashi S. Isolation and characterization of norfloxacin-resistant mutants of Escherichia coli K-12. Antimicrob Agents Chemother. 1986 Aug;30(2):248–253. doi: 10.1128/aac.30.2.248. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Hooper D. C., Wolfson J. S., Ng E. Y., Swartz M. N. Mechanisms of action of and resistance to ciprofloxacin. Am J Med. 1987 Apr 27;82(4A):12–20. [PubMed] [Google Scholar]
  16. Hooper D. C., Wolfson J. S., Souza K. S., Tung C., McHugh G. L., Swartz M. N. Genetic and biochemical characterization of norfloxacin resistance in Escherichia coli. Antimicrob Agents Chemother. 1986 Apr;29(4):639–644. doi: 10.1128/aac.29.4.639. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Hächler H., Cohen S. P., Levy S. B. marA, a regulated locus which controls expression of chromosomal multiple antibiotic resistance in Escherichia coli. J Bacteriol. 1991 Sep;173(17):5532–5538. doi: 10.1128/jb.173.17.5532-5538.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Johnson S. R., Morse S. A. Antibiotic resistance in Neisseria gonorrhoeae: genetics and mechanisms of resistance. Sex Transm Dis. 1988 Oct-Dec;15(4):217–224. doi: 10.1097/00007435-198810000-00008. [DOI] [PubMed] [Google Scholar]
  19. Kohara Y., Akiyama K., Isono K. The physical map of the whole E. coli chromosome: application of a new strategy for rapid analysis and sorting of a large genomic library. Cell. 1987 Jul 31;50(3):495–508. doi: 10.1016/0092-8674(87)90503-4. [DOI] [PubMed] [Google Scholar]
  20. Ramos J. L., Rojo F., Zhou L., Timmis K. N. A family of positive regulators related to the Pseudomonas putida TOL plasmid XylS and the Escherichia coli AraC activators. Nucleic Acids Res. 1990 Apr 25;18(8):2149–2152. doi: 10.1093/nar/18.8.2149. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Ronecker H. J., Rak B. Genetic organization of insertion element IS2 based on a revised nucleotide sequence. Gene. 1987;59(2-3):291–296. doi: 10.1016/0378-1119(87)90337-4. [DOI] [PubMed] [Google Scholar]
  22. Rothstein S. J., Reznikoff W. S. The functional differences in the inverted repeats of Tn5 are caused by a single base pair nonhomology. Cell. 1981 Jan;23(1):191–199. doi: 10.1016/0092-8674(81)90284-1. [DOI] [PubMed] [Google Scholar]
  23. Sanders C. C., Sanders W. E., Jr, Goering R. V., Werner V. Selection of multiple antibiotic resistance by quinolones, beta-lactams, and aminoglycosides with special reference to cross-resistance between unrelated drug classes. Antimicrob Agents Chemother. 1984 Dec;26(6):797–801. doi: 10.1128/aac.26.6.797. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Schollmeier K., Hillen W. Transposon Tn10 contains two structural genes with opposite polarity between tetA and IS10R. J Bacteriol. 1984 Nov;160(2):499–503. doi: 10.1128/jb.160.2.499-503.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Then R. L., Angehrn P. Multiply resistant mutants of Enterobacter cloacae selected by beta-lactam antibiotics. Antimicrob Agents Chemother. 1986 Nov;30(5):684–688. doi: 10.1128/aac.30.5.684. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. White S., Tuttle F. E., Blankenhorn D., Dosch D. C., Slonczewski J. L. pH dependence and gene structure of inaA in Escherichia coli. J Bacteriol. 1992 Mar;174(5):1537–1543. doi: 10.1128/jb.174.5.1537-1543.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Wu J., Weiss B. Two divergently transcribed genes, soxR and soxS, control a superoxide response regulon of Escherichia coli. J Bacteriol. 1991 May;173(9):2864–2871. doi: 10.1128/jb.173.9.2864-2871.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Yanisch-Perron C., Vieira J., Messing J. Improved M13 phage cloning vectors and host strains: nucleotide sequences of the M13mp18 and pUC19 vectors. Gene. 1985;33(1):103–119. doi: 10.1016/0378-1119(85)90120-9. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES