PMID:17040104

Citation	Vidal, LS, Santos, LB, Lage, C and Leitão, AC (2006) Enhanced sensitivity of Escherichia coli uvrB mutants to mitomycin C points to a UV-C distinct repair for DNA adducts.Chem. Res. Toxicol. 19:1351-6
Abstract	Nucleotide excision repair (NER) in Escherichia coli repairs DNA by incising the damaged strand on the 3' and 5' sides of the lesion within pyrimidine dimers and DNA cross-linking adducts. Cross-linking adducts belong to a class of chemical damage to DNA that prevent strand separation, and thus, replication and transcription. For this reason, cross-linking agents such as mitomycin C (MC) have been used in cancer chemotherapy. The mechanisms involved in MC binding to DNA have already been defined; however, the repair of these lesions is not fully understood. Our goal was to study the repair of MC DNA lesions in E. coli cells. Several bacterial strains with specific mutations were tested for cellular inactivation and kinetics of DNA repair through analysis of DNA sedimentation profiles in alkaline sucrose gradients. The results obtained show that uvrB mutants are extremely sensitive to MC in contrast to the other isogenic uvrA and uvrC mutant strains. uvrB mutant strains are unable to repair DNA strand breaks produced by MC. Thus, UvrB might play a NER-uncoupled role in the repair of lesions induced by MC in vivo, different from its role on the repair of lesions produced by UV-C. Also it is suggested that a modified NER system is taking place in the repair of MC-adducts.
Links	PubMed Online version:10.1021/tx060035y
Keywords	Cell Survival; DNA Adducts; DNA Helicases; DNA Repair; Escherichia coli; Escherichia coli Proteins; Mitomycin; Mutation; Rec A Recombinases; Sensitivity and Specificity; Ultraviolet Rays
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Phenotype of	Taxon Information	Genotype Information (if known)	Condition Information	OMP ID	OMP Term Name	ECO ID	ECO Term Name	Notes	Status
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: AB1885 NCBI Taxon ID: 83333	Genotype of Reference Strain: uvrB Genotype of Experimental Strain : uvrB5	Reference Condition:	OMP:0000275	decreased resistance to			truncation mutation was more sensitive to lower mitomycin C concentrations than complete null mutation, uvrB301(de), due to proteins binding competition, figure 2.
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