Skip to main content
PMC home page
Journal of Bacteriology logoLink to Journal of Bacteriology
. 1993 Jan;175(1):251–258. doi: 10.1128/jb.175.1.251-258.1993

Control of transcription of gal repressor and isorepressor genes in Escherichia coli.

M J Weickert 1, S Adhya 1
PMCID: PMC196120  PMID: 8416900

Abstract

Two regulatory proteins, Gal repressor and isorepressor, control the expression of the gal and mgl operons in Escherichia coli. The transcription start sites for galR and galS, the genes for the repressor and isorepressor, were determined by primer extension of in vivo transcripts. Study of the promoter-lacZ gene fusions introduced into the chromosome indicated that galS expression was elevated in cells in which the normal galS gene was interrupted, but not in cells in which the galR gene was deleted. When both genes were disrupted, galS expression was further elevated. Expression from the galS promoter was stimulated by the addition of D-fucose, repressed by glucose, and dependent on cyclic AMP receptor protein (CRP). Expression of a similar gene fusion of the galR promoter to lacZ was unregulated. Both galR and galS genes contain two potential operator sites (OE and OI) and a CRP-binding site. The arrangement of OE, OI, and the CRP-binding site in the galS gene is analogous to the arrangement in the gal and mgl promoters, but the arrangement in galR is atypical. The increased concentration of the isorepressor when inducer is present may facilitate early shutoff of the isorepressor-regulated genes of the gal regulon when inducer (substrate) concentration falls.

Full text

PDF
251

Images in this article

253Image
on p.253

Selected References

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

  1. Adhya S. L., Shapiro J. A. The galactose operon of E. coli K-12. I. Structural and pleiotropic mutations of the operon. Genetics. 1969 Jun;62(2):231–247. doi: 10.1093/genetics/62.2.231. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Adhya S., Miller W. Modulation of the two promoters of the galactose operon of Escherichia coli. Nature. 1979 Jun 7;279(5713):492–494. doi: 10.1038/279492a0. [DOI] [PubMed] [Google Scholar]
  3. BUTTIN G. M'ECANISMES R'EGULATEURS DANS LA BIOSYNTH'ESE DES ENZYMES DU M'ETABOLISME DU GALACTOSE CHEZ ESCHERICHIA COLI K12. I. LA BIOSYNTH'ESE INDUITE DE LA GALACTOKINASE ET L'INDUCTION SIMULTAN'EE DE LA S'EQUENCE ENZYMATIQUE. J Mol Biol. 1963 Aug;7:164–182. doi: 10.1016/s0022-2836(63)80044-3. [DOI] [PubMed] [Google Scholar]
  4. BUTTIN G. M'ECANISMES R'EGULATEURS DANS LA BIOSYNTH'ESE DES ENZYMES DU M'ETABOLISME DU GALACTOSE CHEZ ESCHERICHIA COLI K12. II. LE D'ETERMINISME G'EN'ETIQUE DE LA R'EGULATION. J Mol Biol. 1963 Aug;7:183–205. doi: 10.1016/s0022-2836(63)80045-5. [DOI] [PubMed] [Google Scholar]
  5. Benner-Luger D., Boos W. The mglB sequence of Salmonella typhimurium LT2; promoter analysis by gene fusions and evidence for a divergently oriented gene coding for the mgl repressor. Mol Gen Genet. 1988 Nov;214(3):579–587. doi: 10.1007/BF00330498. [DOI] [PubMed] [Google Scholar]
  6. Boos W., Lengeler J., Hermann K. O., Unsöld H. J. The regulation of the beta-methylgalactoside transport system and of the galactose binding protein of Escherichia coli K12. Eur J Biochem. 1971 Apr 30;19(4):457–470. doi: 10.1111/j.1432-1033.1971.tb01336.x. [DOI] [PubMed] [Google Scholar]
  7. Ganesan A. K., Rotman B. Transport systems for galactose and galactosides in Escherichia coli. I. Genetic determination and regulation of the methyl-galactoside permease. J Mol Biol. 1966 Mar;16(1):42–50. doi: 10.1016/s0022-2836(66)80261-9. [DOI] [PubMed] [Google Scholar]
  8. Gerlach P., Valentin-Hansen P., Bremer E. Transcriptional regulation of the cytR repressor gene of Escherichia coli: autoregulation and positive control by the cAMP/CAP complex. Mol Microbiol. 1990 Mar;4(3):479–488. doi: 10.1111/j.1365-2958.1990.tb00614.x. [DOI] [PubMed] [Google Scholar]
  9. Golding A., Weickert M. J., Tokeson J. P., Garges S., Adhya S. A mutation defining ultrainduction of the Escherichia coli gal operon. J Bacteriol. 1991 Oct;173(19):6294–6296. doi: 10.1128/jb.173.19.6294-6296.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Hawley D. K., McClure W. R. Compilation and analysis of Escherichia coli promoter DNA sequences. Nucleic Acids Res. 1983 Apr 25;11(8):2237–2255. doi: 10.1093/nar/11.8.2237. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Hogg R. W., Voelker C., Von Carlowitz I. Nucleotide sequence and analysis of the mgl operon of Escherichia coli K12. Mol Gen Genet. 1991 Oct;229(3):453–459. doi: 10.1007/BF00267469. [DOI] [PubMed] [Google Scholar]
  12. Irani M., Musso R., Adhya S. Cyclic-AMP-dependent switch in initiation of transcription from the two promoters of the Escherichia coli gal operon: identification and assay of 5'-triphosphate ends of mRNA by GTP:RNA guanyltransferase. J Bacteriol. 1989 Mar;171(3):1623–1630. doi: 10.1128/jb.171.3.1623-1630.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Kalckar H. M., Kurahashi K., Jordan E. HEREDITARY DEFECTS IN GALACTOSE METABOLISM IN ESCHERICHIA COLI MUTANTS, I. DETERMINATION OF ENZYME ACTIVITIES. Proc Natl Acad Sci U S A. 1959 Dec;45(12):1776–1786. doi: 10.1073/pnas.45.12.1776. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Majumdar A., Adhya S. Demonstration of two operator elements in gal: in vitro repressor binding studies. Proc Natl Acad Sci U S A. 1984 Oct;81(19):6100–6104. doi: 10.1073/pnas.81.19.6100. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Majumdar A., Adhya S. Probing the structure of gal operator-repressor complexes. Conformation change in DNA. J Biol Chem. 1987 Sep 25;262(27):13258–13262. [PubMed] [Google Scholar]
  16. Meng L. M., Kilstrup M., Nygaard P. Autoregulation of PurR repressor synthesis and involvement of purR in the regulation of purB, purC, purL, purMN and guaBA expression in Escherichia coli. Eur J Biochem. 1990 Jan 26;187(2):373–379. doi: 10.1111/j.1432-1033.1990.tb15314.x. [DOI] [PubMed] [Google Scholar]
  17. Rolfes R. J., Zalkin H. Autoregulation of Escherichia coli purR requires two control sites downstream of the promoter. J Bacteriol. 1990 Oct;172(10):5758–5766. doi: 10.1128/jb.172.10.5758-5766.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Rotman B., Ganesan A. K., Guzman R. Transport systems for galactose and galactosides in Escherichia coli. II. Substrate and inducer specificities. J Mol Biol. 1968 Sep 14;36(2):247–260. doi: 10.1016/0022-2836(68)90379-3. [DOI] [PubMed] [Google Scholar]
  19. Saedler H., Gullon A., Fiethen L., Starlinger P. Negative control of the galactose operon in E. coli. Mol Gen Genet. 1968;102(1):79–88. doi: 10.1007/BF00341872. [DOI] [PubMed] [Google Scholar]
  20. Tokeson J. P., Garges S., Adhya S. Further inducibility of a constitutive system: ultrainduction of the gal operon. J Bacteriol. 1991 Apr;173(7):2319–2327. doi: 10.1128/jb.173.7.2319-2327.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Travers A. A. Conserved features of coordinately regulated E. coli promoters. Nucleic Acids Res. 1984 Mar 26;12(6):2605–2618. doi: 10.1093/nar/12.6.2605. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Travers A. A. Promoter sequence for stringent control of bacterial ribonucleic acid synthesis. J Bacteriol. 1980 Feb;141(2):973–976. doi: 10.1128/jb.141.2.973-976.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Valentin-Hansen P., Holst B., Søgaard-Andersen L., Martinussen J., Nesvera J., Douthwaite S. R. Design of cAMP-CRP-activated promoters in Escherichia coli. Mol Microbiol. 1991 Feb;5(2):433–437. doi: 10.1111/j.1365-2958.1991.tb02126.x. [DOI] [PubMed] [Google Scholar]
  24. Weickert M. J., Adhya S. A family of bacterial regulators homologous to Gal and Lac repressors. J Biol Chem. 1992 Aug 5;267(22):15869–15874. [PubMed] [Google Scholar]
  25. Weickert M. J., Adhya S. Isorepressor of the gal regulon in Escherichia coli. J Mol Biol. 1992 Jul 5;226(1):69–83. doi: 10.1016/0022-2836(92)90125-4. [DOI] [PubMed] [Google Scholar]
  26. de Boer P. A., Crossley R. E., Rothfield L. I. Isolation and properties of minB, a complex genetic locus involved in correct placement of the division site in Escherichia coli. J Bacteriol. 1988 May;170(5):2106–2112. doi: 10.1128/jb.170.5.2106-2112.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. von Wilcken-Bergmann B., Müller-Hill B. Sequence of galR gene indicates a common evolutionary origin of lac and gal repressor in Escherichia coli. Proc Natl Acad Sci U S A. 1982 Apr;79(8):2427–2431. doi: 10.1073/pnas.79.8.2427. [DOI] [PMC free article] [PubMed] [Google Scholar]

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

RESOURCES