Mutational analysis of interactions between the Gag precursor proteins of murine leukemia viruses.

The yeast two-hybrid system was used to test for interactions among the Gag precursor proteins of three members of the murine leukemia virus family. These Gag proteins all interact with each other in all combinations, but do not interact with the distantly related HIV-1 Gag. A series of deletion mutants of Moloney MuLV were examined to determine the minimal interaction domain. Either one of two regions of Gag was independently sufficient to mediate homodimerization, suggesting multiple points of contact in the precursor. Analysis of a set of point mutations in the CA region revealed a complex pattern of effects on Gag-Gag interactions.