A role for SSU72 in balancing RNA polymerase II transcription elongation and termination.

Interactions of pre-mRNA 3'end factors and the CTD of RNA polymerase II (RNAP II) are required for transcription termination and 3'end processing. Here, we demonstrate that Ssu72p is stably associated with yeast cleavage and polyadenylation factor CPF and provide evidence that it bridges the CPF subunits Pta1p and Ydh1p/Cft2p, the general transcription factor TFIIB, and RNAP II via Rpb2p. Analyses of ssu72-2 mutant cells in the absence and presence of the nuclear exosome component Rrp6p revealed defects in RNAP II transcription elongation and termination. 6-azauracil, that reduces transcription elongation rates, suppressed the ssu72-2 growth defect at 33 degrees C. The sum of our analyses suggests a negative influence of Ssu72p on RNAP II during transcription that affects the commitment to either elongation or termination.