Specificity of mutation by UV light and delayed photoreversal in umuC-defective Escherichia coli K-12: a targeting intermediate at pyrimidine dimers

Journal Article · Wed Apr 01 04:00:00 EST 1987 · J. Bacteriol.; (United States)

OSTI ID:6612439

Bockrath, R; Ruiz-Rubio, M; Bridges, B A

Prototrophic mutants produced by UV light in Escherichia coli K-12 strains with argE3(Oc) and hisG4(Oc) defects are distinguished as backmutations and specific nonsense suppressor mutations. In strains carrying a umuC defect, mutants are not produced unless irradiated cells are incubated and then exposed to photoreversing light (delayed photoreversal mutagenesis). The mutants thus produced are found to be specifically suppressor mutations and not backmutations. The suppressor mutations are primarily glutamine tRNA ochre suppressor mutations, which have been attributed previously to mutation targeted at T = C pyrimidine dimers. In a lexA51 recA441 strain, where the SOS mutagenesis functions are constitutive, targeting at dimers is confirmed by demonstrating that the induction of glutamine tRNA suppressor mutations is susceptible to photoreversal. In the same strain induction of backmutations is not susceptible to photoreversal. Thus delayed photoreversal mutagenesis produces suppressor mutations that can be targeted at pyrimidine dimers and does not produce backmutations that are not targeted at pyrimidine dimers. This correlation supports the idea that delayed photoreversal mutagenesis in umuC defective cells reflects a mutation process arrested at a targeting pyrimidine dimer photoproduct, which is the immediate cause of both the alteration in DNA sequence and the obstruction (unless repaired) to mutation fixation and ultimate expression.

• Research Organization: Univ. of Sussex, Brighton, England
• OSTI ID: 6612439
• Journal Information: J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 4; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

560130* -- Radiation Effects on Microorganisms
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMIDES
AMINO ACIDS
ARGININE
AZOLES
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CARBOXYLIC ACIDS
DNA
ELECTROMAGNETIC RADIATION
ESCHERICHIA COLI
GENETIC EFFECTS
GENETIC RADIATION EFFECTS
GLUTAMINE
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
IMIDAZOLES
MICROORGANISMS
MUTAGENESIS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOREACTIVATION
PYRIMIDINE DIMERS
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
RNA
TRANSFER RNA
ULTRAVIOLET RADIATION