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Gene Review

lexA  -  transcriptional repressor of SOS regulon

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK4035, JW4003, exrA, spr, tsl, ...
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Disease relevance of lexA

  • DNA polymerase I* is a form of the DNA polymerase I isolated from Escherichia coli which are expressing recA/lexA (SOS) functions [1].
  • This sequence is also present upstream of the Geobacter metallireducens lexA gene, indicating that it is the LexA box of this bacterial genus [2].
  • 2AP-reactivation can be distinguished from Weigle-reactivation in that it is not accompanied by an increase in mutagenesis, does not act on the single-stranded DNA bacteriophage phi X174, and occurs in recA and lexA bacteria [3].
  • The plating efficiency of UV-irradiated lambda-phage was drastically reduced in the lexA and recA strains treated with Blm [4].
  • By using this method, the lexA-like genes of Salmonella typhimurium, Erwinia carotovora, Pseudomonas aeruginosa, and P. putida were cloned [5].

High impact information on lexA


Chemical compound and disease context of lexA


Biological context of lexA


Anatomical context of lexA


Associations of lexA with chemical compounds

  • These include three branches that are blocked by the exrA, recB, or uvrD mutation, a fourth branch that is blocked by any of these mutations and is also sensitive to chloramphenicol treatment, and at least one additional branch that is not sensitive to either of these mutations or to chloramphenicol treatment [20].
  • Therefore, we assume that cinnamaldehyde may enhance an error-free recombinational repair system by acting on recA-enzyme activity [21].
  • Coumermycin A1, however, produced a more gradual decline in synthesis rate which is unaffected by defects in the recA or lexA genes [22].
  • Furthermore, this mechanism might be indirectly related to the SOS regulon, because lexA and recA mutants, which block the induction of the SOS response, prevent dnaA induction by MMS and MC [23].
  • Using two independent methods to detect pyrimidine dimers we found that UV irradiated RecA deficient cells removed dimers from their DNA more rapidly if they contained the lexA41 mutation than if they contained the wild-type lexA gene [24].

Enzymatic interactions of lexA

  • RecF, RecO and RecR, three of the important proteins of the RecF pathway of recombination, are also needed for repair of DNA damage due to UV irradiation. recF mutants are not proficient in cleaving LexA repressor in vivo following DNA damage: therefore they show a delay of induction of the SOS response [25].

Regulatory relationships of lexA


Other interactions of lexA


Analytical, diagnostic and therapeutic context of lexA


  1. Characterization of DNA polymerase I*, a form of DNA polymerase I found in Escherichia coli expressing SOS functions. Lackey, D., Krauss, S.W., Linn, S. J. Biol. Chem. (1985) [Pubmed]
  2. Geobacter sulfurreducens has two autoregulated lexA genes whose products do not bind the recA promoter: differing responses of lexA and recA to DNA damage. Jara, M., Núñez, C., Campoy, S., Fernández de Henestrosa, A.R., Lovley, D.R., Barbé, J. J. Bacteriol. (2003) [Pubmed]
  3. 2-aminopurine induced DNA repair in E. coli. Maenhaut-Michel, G., Caillet-Fauquet, P. Mol. Gen. Genet. (1982) [Pubmed]
  4. Genetic activity of bleomycin in Escherichia coli. Yamamoto, K., Hiramoto, T., Shinagawa, H., Fujiwara, Y. Chem. Biol. Interact. (1984) [Pubmed]
  5. One-step cloning system for isolation of bacterial lexA-like genes. Calero, S., Garriga, X., Barbé, J. J. Bacteriol. (1991) [Pubmed]
  6. A role for a small stable RNA in modulating the activity of DNA-binding proteins. Retallack, D.M., Friedman, D.I. Cell (1995) [Pubmed]
  7. LexA and lambda Cl repressors as enzymes: specific cleavage in an intermolecular reaction. Kim, B., Little, J.W. Cell (1993) [Pubmed]
  8. Protein splicing in the maturation of M. tuberculosis recA protein: a mechanism for tolerating a novel class of intervening sequence. Davis, E.O., Jenner, P.J., Brooks, P.C., Colston, M.J., Sedgwick, S.G. Cell (1992) [Pubmed]
  9. Molecular biology. recA: from locus to lattice. McEntee, K. Nature (1992) [Pubmed]
  10. Purification and characterization of the human Rad51 protein, an analogue of E. coli RecA. Benson, F.E., Stasiak, A., West, S.C. EMBO J. (1994) [Pubmed]
  11. 5-Azacytidine: survival and induction of the SOS response in Escherichia coli K-12. Barbé, J., Gibert, I., Guerrero, R. Mutat. Res. (1986) [Pubmed]
  12. Spacing requirements between LexA operator half-sites can be relaxed by fusing the LexA DNA binding domain with some alternative dimerization domains. Oertel-Buchheit, P., Schmidt-Dörr, T., Granger-Schnarr, M., Schnarr, M. J. Mol. Biol. (1993) [Pubmed]
  13. Preferential interactions of the Escherichia coli LexA repressor with anions and protons are coupled to binding the recA operator. Relan, N.K., Jenuwine, E.S., Gumbs, O.H., Shaner, S.L. Biochemistry (1997) [Pubmed]
  14. The recA gene from Clostridium perfringens is induced by methyl methanesulphonate and contains an upstream Cheo box. Johnston, J.L., Sloan, J., Fyfe, J.A., Davies, J.K., Rood, J.I. Microbiology (Reading, Engl.) (1997) [Pubmed]
  15. 'Rec-lac test' for detecting SOS-inducing activity of environmental genotoxic substance. Nunoshiba, T., Nishioka, H. Mutat. Res. (1991) [Pubmed]
  16. Nucleotide sequence of the lexA gene of Escherichia coli K-12. Markham, B.E., Little, J.W., Mount, D.W. Nucleic Acids Res. (1981) [Pubmed]
  17. Induction of the SOS response in Escherichia coli by azidothymidine and dideoxynucleosides. Mamber, S.W., Brookshire, K.W., Forenza, S. Antimicrob. Agents Chemother. (1990) [Pubmed]
  18. Genetic recombination of bacterial plasmid DNA: effect of RecF pathway mutations on plasmid recombination in Escherichia coli. Kolodner, R., Fishel, R.A., Howard, M. J. Bacteriol. (1985) [Pubmed]
  19. Broad host-range vector for efficient expression of foreign genes in gram-negative bacteria. Rangwala, S.H., Fuchs, R.L., Drahos, D.J., Olins, P.O. Biotechnology (N.Y.) (1991) [Pubmed]
  20. Genetic control of multiple pathways of post-replicational repair in uvrB strains of Escherichia coli K-12. Youngs, D.A., Smith, K.C. J. Bacteriol. (1976) [Pubmed]
  21. Analysis of the antimutagenic effect of cinnamaldehyde on chemically induced mutagenesis in Escherichia coli. Ohta, T., Watanabe, K., Moriya, M., Shirasu, Y., Kada, T. Mol. Gen. Genet. (1983) [Pubmed]
  22. Differential effects of antibiotics inhibiting gyrase. Engle, E.C., Manes, S.H., Drlica, K. J. Bacteriol. (1982) [Pubmed]
  23. Expression of the dnaA gene of Escherichia coli is inducible by DNA damage. Quiñones, A., Jüterbock, W.R., Messer, W. Mol. Gen. Genet. (1991) [Pubmed]
  24. Effect of a lexA41(Ts) mutation on DNA repair in recA(Def) derivatives of Escherichia coli K-12. Ganesan, A.K., Hanawalt, P.C. Mol. Gen. Genet. (1985) [Pubmed]
  25. recO and recR mutations delay induction of the SOS response in Escherichia coli. Hegde, S., Sandler, S.J., Clark, A.J., Madiraju, M.V. Mol. Gen. Genet. (1995) [Pubmed]
  26. Study of the expression of UVRA and SSB proteins in vivo in lambda hybrid phages containing the uvrA and ssbA genes of Escherichia coli. Alazard, R.J. Mutat. Res. (1983) [Pubmed]
  27. How Escherichia coli sets different basal levels in SOS operons. Huisman, O., D'Ari, R., Casaregola, S. Biochimie (1982) [Pubmed]
  28. Escherichia coli RecX inhibits RecA recombinase and coprotease activities in vitro and in vivo. Stohl, E.A., Brockman, J.P., Burkle, K.L., Morimatsu, K., Kowalczykowski, S.C., Seifert, H.S. J. Biol. Chem. (2003) [Pubmed]
  29. Enzymatic production of deoxyribonucleic acid double-strand breaks after ultraviolet irradiation of Escherichia coli K-12. Bonura, T., Smith, K.C. J. Bacteriol. (1975) [Pubmed]
  30. Isolation and characterization of mutants of Escherichia coli deficient in induction of mutations by ultraviolet light. Kato, T., Shinoura, Y. Mol. Gen. Genet. (1977) [Pubmed]
  31. Effect of suppressors of SOS-mediated filamentation on sfiA operon expression in Escherichia coli. Huisman, O., D'Ari, R. J. Bacteriol. (1983) [Pubmed]
  32. Clarification of the Escherichia coli genetic map in the 92-minute region containing the ubiCA operon and the plsB, dgk, lexA, and dinF genes. Heide, L., Melzer, M., Siebert, M., Bechthold, A., Schröder, J., Severin, K. J. Bacteriol. (1993) [Pubmed]
  33. Cooperative and salt-resistant binding of lexA protein to non-operator DNA. Schnarr, M., Daune, M. FEBS Lett. (1984) [Pubmed]
  34. Ultraviolet light-induced mutation in UV-resistant, thermosensitive derivatives of lexA-strains of Escherichia coli K-12. Mount, D.W., Kosel, C. Mol. Gen. Genet. (1975) [Pubmed]
  35. Structural and functional characterization of the lexA gene of Xanthomonas campestris pathovar citri. Yang, Y.C., Yang, M.K., Kuo, T.T., Tu, J. Mol. Genet. Genomics (2001) [Pubmed]
  36. Inhibition of recA-mediated strand exchange by adducts of azacytosine-containing DNA and the EcoRII methylase. Huang, Y.C., Friedman, S. J. Biol. Chem. (1991) [Pubmed]
  37. The LexA repressor binds within the deep helical groove of the activated RecA filament. Yu, X., Egelman, E.H. J. Mol. Biol. (1993) [Pubmed]
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