ISOLATION AND ANALYSIS OF THE YEAST TEA1 GENE, WHICH ENCODES A ZINC CLUSTER TY ENHANCER-BINDING PROTEIN

A genetic screen for mutants that affect the activity of internal regu latory sequences of Ty retrotransposons led to the identification of a new gene encoding a DNA-binding protein that interacts with the downs tream enhancer-like region of Ty1 elements. The TEA1 (Ty enhancer acti vator) gene sequence predicts a protein of 86.9 kDa whose N terminus c ontains a zinc cluster and dimerization motif typical of the Gal4-type family of DNA-binding proteins. The C terminus encodes an acidic doma in with a net negative charge of -10 and the ability to mediate transc riptional activation. Like other zinc cluster proteins, purified Tea1 was found to bind to a partially palindromic CGGN(x)CCG repeat motif l ocated in the Ty1 enhancer region. The Ty1 Tea1 binding site has a spa cing of 10 and is located near binding sites for the DNA-binding prote ins Rap1 and Mcm1. Analysis of the phenotype of tea1 deletion mutants confirmed that the TEA1 gene is required for activation from the inter nal Ty1 enhancer characterized in this study and makes a modest contri bution to normal Ty1 levels in the cell. Hence, Tea1, like Rap1, is a member of a small family of downstream activators in Saccharomyces cer evisiae. Further analysis of the Tea1 protein and its interactions may provide insight into the mechanism of downstream activation in yeast cells.