Analysis of ultraviolet light-induced suppressor mutations in the strain of Escherichia coli K-12 AB1157: An implication for molecular mechanisms of UV mutagenesis
✍ Scribed by Kato, Takesi ;Shinoura, Yukiko ;Templin, Ann ;Clark, Alvin J.
- Publisher
- Springer
- Year
- 1980
- Tongue
- English
- Weight
- 895 KB
- Volume
- 180
- Category
- Article
- ISSN
- 0026-8925
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✦ Synopsis
Genetic analysis of histidine independent (His +) revertants induced by ultraviolet light in the his-4 E. coli strain ABl157 was carried out: 83% carried ochre (UAA) suppressor m~atations and 17% carried back mutations to his + or (intragenic?) suppressors not detectably separable from his-4. Using the specialized transducing 2psu 2intphage, which carries supE-supB, it was determined that 87% of the ochre suppressors mapped in the supE-supB region. We were able to deduce that 56% of these affected tRNA~ I" by a CAA--, TAA change in the tRNA gene while 31% affected tRNA2 ~jn by TAG-TAA change. Although we were unable to deduce the base substitution of the remaining 13 %, the results indicate that most of the suppressor mutations are caused by a G:C to A:T transition.
These results suggest that the high incidence of supE-supB region suppressor mutation in E. coli by UV would be a reflection of the general feature of UV mutagenesis; i.e. preferential induction of G:C to A:T transition in repairing nonpairing DNA lesions.