Ssu72 is a phosphatase essential for transcription termination of snoRNAs and specific mRNAs in yeast.

Ssu72 is an essential yeast protein that is involved in transcription. It physically interacts with transcription initiation and termination complexes. In this report, we provide evidence that Ssu72 is a phosphatase that physically interacts with the CTD kinase Kin28 and functionally interacts with the CTD phosphatase Fcp1. A genome-wide expression analysis of mutant ssu72-ts69 during growth in complete medium revealed a number of defects, including the accumulation of a limited number of mRNAs and the read-through transcription of small nucleolar RNAs and of some mRNAs. We hypothesize that Ssu72 plays a key role in the transcription termination of certain transcripts, possibly by promoting RNA polymerase pausing and release. The possibility that the CTD of the largest subunit of RNA polymerase II is a substrate of Ssu72 is discussed.