Deaminase activity on single-stranded DNA (ssDNA) occurs in vitro when APOBEC3G cytidine deaminase forms homotetramers and higher-order complexes.

ABSTRACT: APOBEC3G (A3G) is a cytidine deaminase that catalyzes deamination of deoxycytidine (dC) on single-stranded DNA (ssDNA). The oligomeric state of A3G required to support deaminase activity remains unknown. We show under defined in vitro conditions that full-length and native A3G formed complexes with ssDNA in an A3G concentration-dependent but temperature-independent manner. Complexes assembled and maintained at 4 °C did not have significant deaminase activity, but their enzymatic function could be restored by subsequent incubation at 37 °C. This approach enabled complexes of a defined size range to be isolated and subsequently evaluated for their contribution to enzymatic activity. The composition of A3G bound to ssDNA was determined by protein-protein chemical cross-linking. A3G-ssDNA comp

SUBMITTER: McDougall WM 

PROVIDER: S-EPMC3162426 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature