Partial complementation of the UV sensitivity of Deinococcus radiodurans excision repair mutants by the cloned denV gene of bacteriophage T4.
Deinococcus radiodurans has 2 endonucleases that incise UV-irradiated DNA. UV endonuclease-alpha and UV endonuclease-beta, that are believed to functionally overlap. Both endonucleases must be mutationally inactivated to yield an incisionless, markedly UV-sensitive phenotype. denV, the bacteriophage T4 gene encoding pyrimidine dimer-DNA glycosylase (PD-glycosylase), was introduced and expressed via duplication insertion in D. radiodurans wild-type, and single and double UV endonuclease mutants. The strain deficient in UV endonuclease-alpha has wild-type UV resistance, and the expression of PD-glycosylase exerted no survival effect on this strain or wild-type. Expression of denV increased survival of both the markedly UV-sensitive double mutant and the moderately UV-sensitive strain deficient only in UV endonuclease-beta. In endonuclease-beta-deficient cells phenotypic complementation by denV was almost complete in restoring UV resistance to wild-type levels. These results suggest that UV endonuclease-alpha (which is present in the endonuclease-beta-deficient cells) does not recognize one or more types of cyclobutane dimer incised by the PD-glycosylase or UV endonuclease-beta.
Gutman
P D
PD
Department of Pathology, F.E. Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799.
Yao
H L
HL
Minton
K W
KW
D002875:Chromosomes / Q000648:ultrastructure; D003001:Cloning, Molecular; D045647:DNA Glycosylases; D004260:DNA Repair / Q000528:radiation effects*; D015870:Gene Expression; D005814:Genes, Viral / Q000502:physiology / Q000528:radiation effects*; D005816:Genetic Complementation Test; D006094:Gram-Positive Bacteria / Q000235:genetics* / Q000528:radiation effects; D009154:Mutation; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000378:metabolism; D013604:T-Phages / Q000235:genetics* / Q000528:radiation effects; D014170:Transformation, Genetic; D014466:Ultraviolet Rays
D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C036401:deoxyribopyrimidine endonucleosidase