Figure 1: Repair photocycle of ultraviolet-damaged DNA by E.coli photolyase and the key functional residues in the active site with corresponding repair quantum yields.
From: The molecular origin of high DNA-repair efficiency by photolyase
(a) The repair photocycle of UV-damaged DNA (thymine dimer) by photolyase with six elementary steps including one deactivation, three electron transfer and two bond-breaking reactions. Two competing processes with four main steps reduce the overall repair quantum efficiency. (b) Local structure at the active site with five critical residues (green), the cofactor flavin (orange) and substrate thymine dimer (cyan). The mutants of each of the five residues were examined for their contributions to the modulation of repair efficiency. Note the active site enzyme–substrate contacts are based on A. nidulans photolyase-substrate co-crystal structure. The numbers in parenthesis indicate the corresponding residues in E. coli photolyase. (c) Repair kinetics and repair quantum yields (QY) of wild-type photolyase and the six mutants analysed in this study.
