Using yeast-based assays to dissect human APOBEC3 function

The cytosine deaminases APOBEC3F and -3G (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3F and -3G) were recently shown to be inhibitors of retroviral infectivity.   APOBEC3F and -3G are incorporated into budding virions and once the virus infects a target cell they deaminate cytosine to uracil in the viral cDNA.  This deaminase activity can trigger high levels of mutation and possibly also misreplication and degradation of the viral cDNA, resulting in inhibition of virus infectivity.  However, it is still unclear precisely how these steps occur and how APOBEC3F and -3G are prevented from deaminating the cellular genome. 

The goal of my research project is to identify APOBEC3F and -3G regulatory proteins as well as important functional domains.  In order to accomplish this we have developed a sensitive yeast assay system to simultaneously monitor the cytosine deaminase and protein interaction activities of these APOBEC proteins.