Recognition and Incision of Oxidative Intrastrand Cross-link Lesions by UvrABC Nuclease

摘要: Nucleotide excision repair (NER) is a pathway that removes variety of bulky DNA lesions in both prokaryotic and eukaryotic cells. The perturbation helix structure caused by the oxidative intrastrand could render them good substrates for NER pathway. Here we employed Escherichia coli (E. coli) enzymes, i.e., UvrA, UvrB UvrC, to examine incision efficiency duplex carrying three different cross-link lesions, is, G[8-5]C, G[8-5m]mC, G[8-5m]T, two dithymine photoproducts, namely, cis,syn-cyclobutane pyrimidine dimer (T[c,s]T) pyrimidine(6-4)pyrimidone product (T[6-4]T). Our results showed T[6-4]T was best substrate UvrA binding, followed G [8-5m]mC then T[c,s]T. efficiencies UvrABC incisions these were consistent with their binding affinities: stronger higher rate. In addition, flanking sequences appeared have little effect on affinity toward G[8-5]C as AG[8-5]CA only slightly preferred over CG[8-5] CG. Consistently, exhibited almost no difference rates. Furthermore, investigated thermal stability dodecameric duplexes containing G[8-5m]mC or G[8-5m] T our revealed destabilized duplex, due an increase free energy formation at 37°C, approximately 5.4 kcal/mol 3.6 kcal/mol, respectively. destabilizations those most part, are correlated affinities rates UvrABC. Taken together, from this study suggest might be enzymes vivo.