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. 1971 Jul;123(4):579–584. doi: 10.1042/bj1230579

Effect of point mutations in the lac promoter on transient and severe catabolite repression of the lac operon of Escherichia coli

M D Yudkin 1,*
PMCID: PMC1176997  PMID: 4942449

Abstract

1. Experiments were devised to show whether the point mutations L8 and L29 in the lac promoter alleviate transient repression. 2. Several recombinants were picked from matings between a single F−p+ strain and Hfr strains carrying mutations L8 and L29. All of the 19 p− recombinants tested proved to suffer no transient repression, whereas all of the eight p+ recombinants tested suffered prolonged transient repression. 3. A diploid strain was constructed in which more than 90% of the thiogalactoside transacetylase is synthesized from the episome with a wild-type lac promoter, whereas 100% of the β-galactosidase is synthesized from the chromosome with a promoter carrying mutation L8. In this diploid the synthesis of thiogalactoside transacetylase suffered transient repression but the synthesis of β-galactosidase did not. 4. Exactly similar results were obtained with a diploid strain in which the chromosomal promoter carried mutation L29. 5. The same diploid strains were used in experiments to show whether mutations L8 and L29 alleviate the severe catabolite repression caused by growth in glucose plus gluconate. In both strains glucose+gluconate repressed the synthesis of β-galactosidase much less than the synthesis of thiogalactoside transacetylase. 6. These and previously reported results can be explained by assuming (a) that both mutations L8 and L29 render the lac promoter partially, but not completely, insensitive to catabolite repression, and (b) that transient repression is an exceptionally severe form of catabolite repression.

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Selected References

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

  1. Pastan I., Perlman R. L. The role of the lac promotor locus in the regulation of beta-galactosidase synthesis by cyclic 3',5'-adenosine monophosphate. Proc Natl Acad Sci U S A. 1968 Dec;61(4):1336–1342. doi: 10.1073/pnas.61.4.1336. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Perlman R. L., Pastan I. Regulation of beta-galactosidase synthesis in Escherichia coli by cyclic adenosine 3',5'-monophosphate. J Biol Chem. 1968 Oct 25;243(20):5420–5427. [PubMed] [Google Scholar]
  3. Signer E. R., Beckwith J. R., Brenner S. Mapping of suppressor loci in Escherichia coli. J Mol Biol. 1965 Nov;14(1):153–166. doi: 10.1016/s0022-2836(65)80237-6. [DOI] [PubMed] [Google Scholar]
  4. Silverstone A. E., Arditti R. R., Magasanik B. Catabolite-insensitive revertants of lac promoter mutants. Proc Natl Acad Sci U S A. 1970 Jul;66(3):773–779. doi: 10.1073/pnas.66.3.773. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Silverstone A. E., Magasanik B., Reznikoff W. S., Miller J. H., Beckwith J. R. Catabolite sensitive site of the lac operon. Nature. 1969 Mar 15;221(5185):1012–1014. doi: 10.1038/2211012b0. [DOI] [PubMed] [Google Scholar]
  6. Tyler B., Loomis W. F., Jr, Magasanik B. Transient repression of the lac operon. J Bacteriol. 1967 Dec;94(6):2001–2011. doi: 10.1128/jb.94.6.2001-2011.1967. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Tyler B., Magasanik B. Molecular basis of transient repression of beta-galactosidase in Escherichia coli. J Bacteriol. 1969 Feb;97(2):550–556. doi: 10.1128/jb.97.2.550-556.1969. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Ullmann A., Monod J. Cyclic AMP as an antagonist of catabolite repression in Escherichia coli. FEBS Lett. 1968 Nov;2(1):57–60. doi: 10.1016/0014-5793(68)80100-0. [DOI] [PubMed] [Google Scholar]
  9. Yudkin M. D. Catabolite repression of the lac operon. Effect of mutations in the lac promoter. Biochem J. 1970 Aug;118(5):741–746. doi: 10.1042/bj1180741. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Yudkin M. D. Catabolite repression of the lac operon. Separt epressionof two enzymes. Biochem J. 1969 Sep;114(2):313–319. doi: 10.1042/bj1140313. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Yudkin M. D. Catabolite repression of the lac operon. The contribution f trascriptional repression. Biochem J. 1969 Sep;114(2):307–311. doi: 10.1042/bj1140307. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Yudkin M. D. Transient repression of beta-galactosidase synthesis: effect of growth history. Biochim Biophys Acta. 1969 Sep 17;190(1):220–221. doi: 10.1016/0005-2787(69)90173-7. [DOI] [PubMed] [Google Scholar]
  13. Yudkin M. D. Transient repression of the lac operon - the effect of a lac promoter deletion. FEBS Lett. 1970 Oct 5;10(3):156–158. doi: 10.1016/0014-5793(70)80441-0. [DOI] [PubMed] [Google Scholar]
  14. Zubay G., Lederman M. DNA-directed peptide synthesis. VI. Regulating the expression of the lac operon in a cell-free system. Proc Natl Acad Sci U S A. 1969 Feb;62(2):550–557. doi: 10.1073/pnas.62.2.550. [DOI] [PMC free article] [PubMed] [Google Scholar]

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