Tup1-Ssn6 Interacts with Multiple Class I Histone Deacetylases in Vivo

The Tup1-Ssn6 corepressor complex in Saccharomyces cerevisiae represses the transcription of a diverse set of genes. Chromatin is an important component of Tup1-Ssn6-mediated repression. Tup1 binds to underacetylated histone tails and requires multiple histone deacetylases (HDACs) for its repressive functions. Here, we describe physical interactions of the corepressor complex with the class I HDACs Rpd3, Hos2, and Hos1. In contrast, no in vivo interaction was observed between Tup-Ssn6 and Hda1, a class II HDAC. We demonstrate that Rpd3 interacts with both Tup1 and Ssn6. Rpd3 and Hos2 interact with Ssn6 independently of Tup1 via distinct tetratricopeptide domains within Ssn6, suggesting that these two HDACs may contact the corepressor at the same time.