Interactions of human O(6)-alkylguanine-DNA alkyltransferase (AGT) with short double-stranded DNAs.

ABSTRACT: O(6)-alkylguanine-DNA alkyltransferase (AGT) is a ubiquitous enzyme with an amino acid sequence that is conserved in Eubacteria, Archaea, and Eukarya. It repairs O(6)-alkylguanine and O(4)-alkylthymine adducts in single-stranded and duplex DNAs. In performing these functions, AGT must partition between adduct-containing sites and the large excess of adduct-free DNA distributed throughout the genome. Here, we characterize the binding of human AGT to linear double-stranded, adduct-free DNAs ranging in length from 11 bp to 2686 bp. Moderately cooperative binding (22.6 +/- 3.7 < or = omega < or = 145.0 +/- 37.0) results in an all-or-nothing association pattern on short templates. The apparent binding site size S(app) (mean = 4.39 +/- 0.02 bp) oscillates with increasing template length. Oscilla

SUBMITTER: Melikishvili M 

PROVIDER: S-EPMC2801566 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature