Mechanisms of uv mutagenesis in yeast and E. coli

Conference · Sat Jan 01 04:00:00 EST 1983

OSTI ID:6095826

Lawrence, C; Christensen, R; Christensen, J R; O'Brien, T

Experiments investigating ultraviolet light mutagenesis in either bakers' yeast, Saccharomyces cerevisiae, or E. coli have led to the following conclusions. First, cyclobutane pyrimidine dimers cause most mutations in both organisms; pyrimidine adducts, such as PyC, can account at best for only a small proportion. 86 percent of forward mutations induced at the E. coli lacI locus can be abolished by photoreactivation under conditions which do not alter the level of recA induction. About 75 percent of the forward mutations induced at the CAN1 locus of yeast could be removed by photoreactivation, a value that lies within the range observed previously for the reversion of CYC1 alleles (60 percent - 97 percent). Second, about 10 percent of the lacI forward mutations are untargeted, a smaller fraction than found previously for cycl-91 reversion in yeast. It is not yet clear whether the two species are really different in this respect, of whether the cycl-91 reversion site is a typical of the yeast genome at large. Third, analysis of reversion frequencies of 20 mutant alleles suggests that about 10 to 25 percent of all replication errors produced by mutagenic mechanisms in uv-irradiated yeast involve additions or deletions of base-pairs, indicating that error-prone repair does not just produce substitutions. Last, the REV1 locus in yeast is concerned with the induction of frameshift mutations at some, but not all, genetic sites, just as found previously for substitution mutations. The function of the REV3 gene is more widely, though not universally, required while the function of the RAD6 gene, like that of the recA locus in E. coli, appears to be necessary for all kinds of uv mutagenesis. E coli genes comparable to REV1 and REV3 have not yet been described; conversely, there does not yet appear to be a yeast equivalent of umuC.

• Research Organization: Rochester Univ., NY (USA)
• DOE Contract Number: AC02-76EV03490
• OSTI ID: 6095826
• Report Number(s): DOE/EV/03490-2284; CONF-830440-4; ON: DE83013219
• Country of Publication: United States
• Language: English

Related Subjects

560131* -- Radiation Effects on Microorganisms-- Basic Studies-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
ELECTROMAGNETIC RADIATION
ESCHERICHIA COLI
FUNGI
GENES
MICROORGANISMS
MUTAGENESIS
MUTATION FREQUENCY
MUTATIONS
PHOTOREACTIVATION
PLANTS
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
SACCHAROMYCES
SACCHAROMYCES CEREVISIAE
ULTRAVIOLET RADIATION
YEASTS