Single-stranded DNA scanning and deamination by APOBEC3G cytidine deaminase at single molecule resolution.

ABSTRACT: APOBEC3G (Apo3G) is a single-stranded (ss)DNA cytosine deaminase that eliminates HIV-1 infectivity by converting C → U in numerous small target motifs on the minus viral cDNA. Apo3G deaminates linear ssDNA in vitro with pronounced spatial asymmetry favoring the 3' → 5' direction. A similar polarity observed in vivo is believed responsible for initiating localized C → T mutational gradients that inactivate the virus. When compared with double-stranded (ds)DNA scanning enzymes, e.g. DNA glycosylases that excise rare aberrant bases, there is a paucity of mechanistic studies on ssDNA scanning enzymes. Here, we investigate ssDNA scanning and motif-targeting mechanisms for Apo3G using single molecule Förster resonance energy transfer. We address the specific issue of deamination asymmetry within

SUBMITTER: Senavirathne G 

PROVIDER: S-EPMC3346118 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature