ROS1 5-methylcytosine DNA glycosylase is a slow-turnover catalyst that initiates DNA demethylation in a distributive fashion.

ABSTRACT: Arabidopsis ROS1 belongs to a family of plant 5-methycytosine DNA glycosylases that initiate DNA demethylation through base excision. ROS1 displays the remarkable capacity to excise 5-meC, and to a lesser extent T, while retaining the ability to discriminate effectively against C and U. We found that replacement of the C5-methyl group by halogen substituents greatly decreased excision of the target base. Furthermore, 5-meC was excised more efficiently from mismatches, whereas excision of T only occurred when mispaired with G. These results suggest that ROS1 specificity arises by a combination of selective recognition at the active site and thermodynamic stability of the target base. We also found that ROS1 is a low-turnover catalyst because it binds tightly to the abasic site left after 5-

SUBMITTER: Ponferrada-Marin MI 

PROVIDER: S-EPMC2715244 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature