FCP1, a Phosphatase Specific for the Heptapeptide Repeat of the Largest Subunit of RNA Polymerase II, Stimulates Transcription Elongation

Abstract

FCP1, a phosphatase specific for the carboxy-terminal domain of RNA polymerase II (RNAP II), was found to stimulate transcript elongation by RNAP II in vitro and in vivo. This activity is independent of and distinct from the elongation-stimulatory activity associated with transcription factor IIF (TFIIF), and the elongation effects of TFIIF and FCP1 were found to be additive. Genetic experiments resulted in the isolation of several distinct fcp1 alleles. One of these alleles was found to suppress the slow-growth phenotype associated with either the reduction of intracellular nucleotide concentrations or the inhibition of other transcription elongation factors. Importantly, this allele of fcp1 was found to be lethal when combined individually with two mutations in the second-largest subunit of RNAP II, which had been shown previously to affect transcription elongation.

We thank M. Hampsey for discussions, J. Greenblatt for yeast strain JA830, F. Winston for strain FY1114 and plasmid FB1101pBM25, R. Young for strains Z103 and Z106, and D. Luse for plasmid pML20-47. We also thank S. J. Conaway for RAP30 mutants and Z. Burton for RAP74 mutants. We also thank members of the Reinberg laboratory for helpful suggestions and M. Hampsey and E. Friedl for comments on the manuscript.

This work was supported by a grant from the NIH (GM-37120) and the Howard Hughes Medical Institute to D.R.

S. S. Mandal and H. Cho contributed equally to this work.