Summary
The lexA41 allele of Escherichia coli encodes a semidefective mutant repressor that is also resistant to RecA facilitated cleavage. Cells harboring the lexA41 allele were found previously to repress only a subset of operons in the SOS regulon. lexA41 cells cannot promote SOS mutagenesis, presumably because one or more operons required for mutagenesis are repressed by this mutant repressor. Using the lac regulatory system to increase the expression of the umuDC operon, we were able to restore mutagenesis in the lexA41 mutant. We conclude that the products of the umuDC operon appear to be uniquely limiting in this mutant.
This is a preview of subscription content, log in via an institution to check access.
References
Bagg A, Kenyon CJ, Walker GC (1981) Inducibility of a gene product required for UV and chemical mutagenesis in Escherichia coli. Proc Natl Acad Sci USA 78:5749–5753
Blanco M, Herrera G, Collado P, Rebollo JE, Botella LM (1982) Influence of RecA protein on inducible mutagenesis. Biochimie 64:633–636
Echols H (1982) Mutation rate: some biological and biochemical considerations. Biochimie 64:571–575
Ennis DG, Fisher B, Edmiston S, Mount DW (1985) Dual role for Escherichia coli RecA protein in SOS mutagenesis. Proc Natl Acad Sci USA 82:3325–3329
Krueger JH, Elledge SJ, Walker GC (1983) Isolation and characterization of Tn5 insertion mutations in lexA gene of Escherichia coli. J Bacteriol 153:1368–1379
Little JW (1984) Autodigestion of lexA and phage repressors. Proc Natl Acad Sci USA 81:1375–1379
Little JW, Mount DW (1982) The SOS regulatory system of Escherichia coli. Cell 29:11–22
Markham BE, Little JW, Mount DW (1981) Nucleotide sequence of the lexA gene of Escherichia coli K-12. Nucleic Acids Res 9:4149–4161
Markham BE, Harper JE, Mount DW, Sancar GB, Sancar A, Rupp WD, Kenyon CJ, Walker GC (1984) Analysis of mRNA synthesis following induction of the Escherichia coli SOS system. J Mol Biol 177:237–248
Marsh L, Walker GC (1985) Cold sensitivity induced by overproduction of UmuDC in Escherichia coli. J Bacteriol 162:155–161
Marsh L, Walker GC (1987) New phenotypes associated with mucAB: alteration of a MucA sequence homologous to the LexA cleavage site. J Bacteriol 169:1818–1823
Mount DW (1977) A mutant of Escherichia coli showing constitutive expression of the lysogenic induction and error prone DNA repair pathways. Proc Natl Acad Sci USA 74:300–304
Mount DW, Kosel C (1975) Ultraviolet light induced mutation in UV resistant, thermosensitive derivatives of lexA -strains of Escherichia coli K-12. Mol Gen Genet 136:95–106
Mount DW, Low KB, Edmiston S (1972) Dominant mutations (lex) in Escherichia coli K-12 which affect radiation sensitivity and frequency of ultraviolet light induced mutations. J Bacteriol 112:886–893
Mount DW, Kosel CK, Walker A (1976) Inducible, error free DNA repair in tsl recA mutants of E. coli. Mol Gen Genet 146:37–41
Perry KL, Elledge SJ, Mitchell BB, Marsh L, Walker GC (1985) umuDC and mucAB operons whose products are required for UV light-and chemical-induced mutagenesis: UmuD, MucA and LexA proteins share homology. Proc Natl Acad Sci USA 82:4331–4335
Peterson KR, Mount DW (1987) Differential repression of SOS genes by unstable LexA41 (Tsl-1) protein causes a “split phenotype” in Escherichia coli K-12. J Mol Biol 193:27–40
Roberts TM, Kachich R, Ptashne M (1979) A general method for maximizing the expression of a cloned gene. Proc Natl Acad Sci USA 76:760–764
Slilaty SN, Little JW (1987) Lysine-156 and Serine-119 are required for LexA repressor cleavage: a possible mechanism. Proc Natl Acad Sci USA 84:3987–3991
Walker AC (1973) Ph D Dissertation. University of Arizona, Tucson, Arizona, USA
Walker GC (1984) Mutagenesis and inducible responses to deoxyribonucleic acid damage in Escherichia coli. Microbiol Rev 48:60–93
Weigle JJ (1953) Induction of mutation in a bacterial virus. Proc Natl Acad Sci USA 39:628–636
Wertman KF, Mount DW (1985) Nucleotide sequence binding specificity of the LexA repressor of Escherichia coli K-12. J Bacteriol 163:376–384
Witkin EM, Kogoma T (1984) Involvement of the activated form of RecA protein in SOS mutagenesis and stable DNA replication in Escherichia coli. Proc Natl Acad Sci USA 81:7539–7543
Author information
Authors and Affiliations
Additional information
Communicated by R. Devoret
Rights and permissions
About this article
Cite this article
Ennis, D.G., Peterson, K.R. & Mount, D.W. Increased expression of the Escherichia coli umuDC operon restores SOS mutagenesis in lexA41 cells. Mol Gen Genet 213, 541–544 (1988). https://doi.org/10.1007/BF00339628
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00339628