Residues in the WD Repeats of Tup1 Required for Interaction with α2

Abstract

The yeast transcriptional repressor Tup1 contains seven WD repeats which interact with the DNA-binding protein α2. We have identified mutations in Tup1 that disrupt this interaction. The positions of the amino acids changed by these mutations are consistent with Tup1 being folded into a seven-bladed propeller like that formed by another WD repeat-containing protein, the β subunit of the heterotrimeric G protein used in signal transduction. Our results also indicate that the interaction between Tup1 and α2 resembles the interaction between Gβ and G α, suggesting that a similar structural interface is formed by WD repeat proteins that are used in both transcriptional regulation and signal transduction.