Summary
In Escherichia coli B/r the expression of UV inducible (SOS) functions is under the control of the recA and lexA genes. In this study we have characterized mutants which are altered in their ability to express SOS functions. These mutants were isolated as UV resistant UV nonmutable (Rnm) derivatives of the lexA102 uvrA155 mutant strain WP51. The UV resistance of these Rnm strains is a result of the suppression of lexA102 mediated UV sensitivity. Genetic mapping of rnm mutations shows that the two predominant classes, rnmA and rnmB, map in or very near the lexA and recA genes respectively.
rnmA mutations differ from rnmB with respectively recA protein synthesis. rnmA mutations do not restore the ability to express high levels of recA protein after UV treatment whereas rnmB mutations result in constitutive expression of high levels of recA protein. However, both rnmA and rnmB mutant strains inhibit postirradiation DNA degradation. This shows that in rnmA strains, high levels of recA protein are not needed to inhibit postirradiation DNA degradation.
The genetic map location and constitutive expression of recA protein synthesis resulting from rnmB mutations suggests that they are operator constitutive mutations of the recA gene. The result that the lexA + gene is required for the expression of UV mutagenesis in rnmB mutants shows that high levels of recA protein do not circumvent the need for the lexA + gene product in this process. Thus, while the lexA gene product is required for the induction of recA protein synthesis, lexA must have an additional role in UV induced mutagenesis.
Similar content being viewed by others
References
Bachman, B.J.: Pedigrees of some mutant strains of Escherichia coli K-12. Bacteriol. Rev. 36, 525–557 (1972)
Bachmann, B.J., Low, K.B., Taylor, A.L.: Recalibrated linkage map of Escherichia coli K-12. Bacteriol. Rev. 40, 116–167 (1976)
Bailone, A., Levine, A., Devoret, R.: In vivo inactivation of prophage λ repressor. J. Mol. Biol. 131, 553–572 (1979)
Boyer, H.W., Roulland-Dussoix, D.: A complementation analysis of the restriction and modification of DNA in Escherichia coli. J. Mol. Biol. 41, 459–472 (1969)
Castellazzi, M., George, J., Buttin, G.: Prophage induction and cell division in E. coli. Mol. Gen. Genet. 119, 139–152 (1972)
Clark, A.J., Volkert, M.R.: A new classification of pathways repairing pyrimidine dimer damage in DNA. In: DNA repair mechanisms, P.C. Hanawalt, E.C. Friedberg, and C.F. Fox (eds.). New York: Academic Press 1978
Clark, A.J., Volkert, M.R., Margossian, L.J.: A role for recF in repair of UV damage to DNA. Cold Spring Harbor Symp. Quant. Biol. XLIII:887–892 (1978)
Day, R.S.: UV-induced alleviation of K specific restriction of Bacteriophage-λ. J. Virol. 21, 1249–1251 (1977)
Defais, M., Fauquet, P., Radman, M., Errera, M.: Ultraviolet reactivation and Ultraviolet mutagenesis of λ in different genetic systems. Virology 43, 495–503 (1971)
Donch, J., Green, M.H.L., Greenberg, J.: Conditional induction of λ prophage in exrA mutants of Escherichia coli. Genet. Res. Camb. 17, 161–163 (1971)
Donch, J., Greenberg, J., Green, M.H.L.: Repression of induction by UV of λ phage by the exrA mutations in Escherichia coli. Genet. Res. Camb. 15, 87–97 (1970)
Emmerson, P.T., West, S.C.: Identification of protein X of Escherichia coli as the recA +/tif + gene product. Mol. Gen. Genet. 155, 77–85 (1977)
Gudas, L.J., Mount, D.W.: Identification of the recA (tif) gene product of Escherichia coli. Proc. Natl. Acad. Sci. U.S.A. 74, 5280–5284 (1977)
Gudas, L.J., Pardee, A.B.: Model for regulation of Escherichia coli DNA repair functions. Proc. Natl. Acad. Sci. U.S.A. 72, 2330–2334 (1975)
Kato, T., Shinoura, Y.: Isolation and characterization of mutants of Escherichia coli deficient in induction of mutations by Ultraviolet light. Mol. Gen. Genet. 156, 121–131 (1977)
Kirby, E.P., Jacob, F., Goldthwait, D.A.: Prophage induction and filament formation in a mutant strain of Escherichia coli. Proc. Natl. Acad. Sci. U.S.A. 58, 1903–1910 (1967)
Little, J.W., Kleid, D.G.: Escherichia coli protein X is the recA gene product. J. Biol. Chem. 252, 6251–6252 (1977)
McEntee, K.M.: Protein X is the product of the recA gene of Escherichia coli. Proc. Natl. Acad. Sci. U.S.A. 74, 5275–5279 (1977)
Mount, D.M.: A mutant of Escherichia coli showing constitutive expression of the lysogenic induction and error-prone DNA repair pathways. Proc. Natl. Acad. Sci. U.S.A. 74, 300–304 (1977)
Mount, D.W., Donch, J.J.: A genetic nomenclature for lex and exr alleles in Escherichia coli. Mutat. Res. 36, 237–240 (1976)
Mount, D.W., Walker, A.C., Kosel, C.: Suppression of lex mutations affecting deoxyribonucleic acid repair in Escherichia coli K-12 by closely linked thermosensitive mutations. J. Bacteriol. 116, 950–956 (1973)
Pacelli, L.Z., Edminston, S.H., Mount, D.W.: Isolation and characterization of amber mutations in the lexA gene of Escherichia coli K-12. J. Bacteriol. 137 568–573 (1979)
Radman, M.: Phenomenology of an inducible mutagenic DNA repair pathway in Escherichia coli: SOS repair hypothesis. In: Molecular and environmental aspects of mutagenesis, Prakash, Sherman, Miller, Lawrence and Taber (eds.) Springfield, Illinois: Charles C. Thomas, 1974
Roberts, J.W., Roberts, C.W.: Proteolytic cleavage of bacteriophage lambda repressor in induction. Proc. Natl. Acad. Sci. U.S.A. 72, 147–151 (1975)
Robert, J.W., Roberts, C.W., Mount, D.: Inactivation and proteolytic cleavage of phage λ repressor in vitro in an ATP-dependent reaction. Proc. Natl. Acad. Sci. U.S.A. 74, 2283–2287 (1977)
Rothman, R.H., Clark, A.J.: The dependence of postreplication repair on uvrB in a recF mutant of Escherichia coli K-12. Mol. Gen. Genet. 155, 279–286 (1977)
Satta, G., Gudas, L.J., Pardee, A.B.: Degradation of Escherichia coli DNA: evidence for limitation in vivo by Protein X the recA gene product. Mol. Gen. Genet. 168, 69–80 (1979)
Shibata, G., DasGupta, C., Cunningham, R.P., Radding, C.M.: Purified Escherichia coli recA protein catalyzes homologus pairing of superhelical DNA and single-stranded fragments. Proc. Natl. Acad. Sci. U.S.A. 76, 1638–1642 (1979)
Volkert, M.R., George, D.L., Witkin, E.M.: Partial suppression of the LexA phenotype by mutations (rnm) which restore ultraviolet resistance but not ultraviolet mutability to escherichia coli B/r uvr A lexA. Mutat. Res. 36, 17–28 (1976)
Weinstock, G.M., McEntee, K., Lehman, I.R.: ATP-dependent renaturation of DNA catalyzed by the recA protein of Escherichia coli. Proc. Natl. Acad. Sci. U.S.A. 76, 126–130 (1979)
Witkin, E.M.: Genetics of resistance to radiation in Escherichia coli. Genetics 32, 221–248 (1947)
Witkin, E.M.: Thermal enhancement of ultraviolet mutability in a tif-1 uvr A derivative of Escherichia coli B/r: evidence that ultraviolet mutagenesis depends upon an inducible function. Proc. Natl. Acad. Sci. U.S.A. 71, 1930–1934 (1974)
Witkin, E.M.: Ultraviolet mutagenesis and inducible DNA repair in Escherichia coli. Bacteriol. Rev. 40, 869–907 (1976)
Witkin, E.M., Parisi, E.C.: Bromouracil mutagenesis: Mispairing or misrepair? Mutat. Res. 25, 407–409 (1974)
Author information
Authors and Affiliations
Additional information
Communicated by M.M. Green
Rights and permissions
About this article
Cite this article
Volkert, M.R., Spencer, D.F. & Clark, A.J. Indirect and intragenic suppression of the lexA102 mutation in E. coli B/r. Molec. Gen. Genet. 177, 129–137 (1979). https://doi.org/10.1007/BF00267262
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00267262