DNA SEQUENCE ANALYSIS OF MUTAGENICITY AND SITE SPECIFICITY OF ETHYL METHANESULFONATE IN Uvr⁺ AND UvrB ^- STRAINS OF ESCHERICHIA COLI

Philip A. Burns ¹, Frances L. Allen ¹, and Barry W. Glickman ¹

¹ Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3 Canada

EMS-induced mutations within a 180 base pair region of the lacI gene of E. coli were cloned and sequenced. In total, 105 and 79 EMS-induced mutations from a Uvr⁺ and a UvrB^- strain, respectively, were sequenced. The specificity of EMS-induced mutagenesis was very similar in the two strians; G:C A:T transitions accounted for all but three of the mutants. The overall frequency of induced mutation was fivefold higher in the UvrB^- strain compared to the Uvr⁺ strain. This demonstrates, at the DNA sequence level, that the presumed pre-mutagenic lesion, O⁶-ethylguanine, is subject to repair by the uvrABC excision repair system of E. coli. An analysis of mutation frequencies with respect to neighboring base sequence, in the two strains, shows that O⁶-ethylguanine lesions adjacent to A:T base pairs present better targets for the excision repair machinery than those not adjacent to A:T base pairs.

This article has been cited by other articles:

				K. Ominato, H. Akita, A. Suzuki, F. Kijima, T. Yoshino, M. Yoshino, Y. Chiba, H. Onouchi, and S. Naito Identification of a Short Highly Conserved Amino Acid Sequence as the Functional Region Required for Posttranscriptional Autoregulation of the Cystathionine gamma -Synthase Gene in Arabidopsis J. Biol. Chem., September 20, 2002; 277(39): 36380 - 36386. [Abstract] [Full Text] [PDF]

				A. Bentley, B. MacLennan, J. Calvo, and C. R. Dearolf Targeted Recovery of Mutations in Drosophila Genetics, November 1, 2000; 156(3): 1169 - 1173. [Abstract] [Full Text]

				B. Singer and B. Hang Nucleic acid sequence and repair: role of adduct, neighbor bases and enzyme specificity Carcinogenesis, June 1, 2000; 21(6): 1071 - 1078. [Full Text] [PDF]

				A. Inga, F.-X. Chen, P. Monti, A. Aprile, P. Campomenosi, P. Menichini, L. Ottaggio, S. Viaggi, A. Abbondandolo, B. Gold, et al. N-(2-Chloroethyl)-N-nitrosourea Tethered to Lexitropsin Induces Minor Groove Lesions at the p53 cDNA That Are More Cytotoxic than Mutagenic Cancer Res., February 1, 1999; 59(3): 689 - 695. [Abstract] [Full Text] [PDF]

				J. G. de Boer and B. W. Glickman The lacI Gene as a Target for Mutation in Transgenic Rodents and Escherichia coli Genetics, April 1, 1998; 148(4): 1441 - 1451. [Abstract] [Full Text] [PDF]