Ssu72 phosphatase-dependent erasure of phospho-Ser7 marks on the RNA polymerase II C-terminal domain is essential for viability and transcription termination.

The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) serves an important role in coordinating stage-specific recruitment and release of cellular machines during transcription. Dynamic placement and removal of phosphorylation marks on different residues of a repeating heptapeptide (YSPTSPS) of the CTD underlies the engagement ...
of relevant cellular machinery. Whereas sequential placement of phosphorylation marks is well explored, genome-wide engagement of phosphatases that remove these CTD marks is poorly understood. In particular, identifying the enzyme that erases phospho-Ser7 (Ser7-P) marks is especially important, because we find that substituting this residue with a glutamate, a phospho-mimic, is lethal. Our observations implicate Ssu72 as a Ser7-P phosphatase. We report that removal of all phospho-CTD marks during transcription termination is mechanistically coupled. An inability to remove these marks prevents Pol II from terminating efficiently and will likely impede subsequent assembly into the pre-initiation complex.
Mesh Terms:
Amino Acid Motifs, Amino Acid Substitution, Mutation, Missense, Phosphoprotein Phosphatases, Protein Structure, Tertiary, RNA Polymerase II, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Serine, Transcription, Genetic, mRNA Cleavage and Polyadenylation Factors
J. Biol. Chem.
Date: Mar. 09, 2012
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