MAPPING THE MULTIMERIZATION DOMAINS OF THE GAG PROTEIN OF YEAST RETROTRANSPOSON TY1

The two-hybrid system was used to define regions of the Ty1 Gag protei n responsible for multimerization. Gag truncations lacking the first 1 46 or the last 97 amino acids (Gag is 440 amino acids in length) inter act. A severely C-terminally truncated molecule (lacking the last 207 amino acids) was the smallest truncation to interact, suggesting that some protein-protein interactions between Gag molecules are mediated t hrough the first 233 amino acids. However, an internal deletion of ami no acids 147 to 233 does not abolish Gag-Gag interaction, indicating t hat more than one region can mediate Gag interaction, Surprisingly we found that a truncation lacking the last 97 amino acids interacts with itself but not with full-length Gag, This is apparently due to an art ifact of the two-hybrid assay, since these same molecules coassemble w ith wild-type Gag into Ty1 virus-like particles.