• Register
X
Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

X

Leaving Community

Are you sure you want to leave this community? Leaving the community will revoke any permissions you have been granted in this community.

No
Yes

Role for the Ssu72 C-terminal domain phosphatase in RNA polymerase II transcription elongation.

The RNA polymerase II (RNAP II) transcription cycle is accompanied by changes in the phosphorylation status of the C-terminal domain (CTD), a reiterated heptapeptide sequence (Y(1)S(2)P(3)T(4)S(5)P(6)S(7)) present at the C terminus of the largest RNAP II subunit. One of the enzymes involved in this process is Ssu72, a CTD phosphatase with specificity for serine-5-P. Here we report that the ssu72-2-encoded Ssu72-R129A protein is catalytically impaired in vitro and that the ssu72-2 mutant accumulates the serine-5-P form of RNAP II in vivo. An in vitro transcription system derived from the ssu72-2 mutant exhibits impaired elongation efficiency. Mutations in RPB1 and RPB2, the genes encoding the two largest subunits of RNAP II, were identified as suppressors of ssu72-2. The rpb1-1001 suppressor encodes an R1281A replacement, whereas rpb2-1001 encodes an R983G replacement. This information led us to identify the previously defined rpb2-4 and rpb2-10 alleles, which encode catalytically slow forms of RNAP II, as additional suppressors of ssu72-2. Furthermore, deletion of SPT4, which encodes a subunit of the Spt4-Spt5 early elongation complex, also suppresses ssu72-2, whereas the spt5-242 allele is suppressed by rpb2-1001. These results define Ssu72 as a transcription elongation factor. We propose a model in which Ssu72 catalyzes serine-5-P dephosphorylation subsequent to addition of the 7-methylguanosine cap on pre-mRNA in a manner that facilitates the RNAP II transition into the elongation stage of the transcription cycle.

Pubmed ID: 17101794

Authors

  • Reyes-Reyes M
  • Hampsey M

Journal

Molecular and cellular biology

Publication Data

February 19, 2007

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM 008360
  • Agency: NIGMS NIH HHS, Id: GM 55145
  • Agency: NIGMS NIH HHS, Id: GM 58389
  • Agency: NIGMS NIH HHS, Id: R01 GM 39484
  • Agency: NIGMS NIH HHS, Id: R01 GM 68887

Mesh Terms

  • Alanine
  • Alleles
  • Amino Acid Sequence
  • Arginine
  • Carrier Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA, Fungal
  • Models, Genetic
  • Molecular Sequence Data
  • Nuclear Proteins
  • Phenotype
  • Phosphoprotein Phosphatases
  • Protein Binding
  • Protein Structure, Secondary
  • RNA Polymerase II
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Sequence Analysis, DNA
  • Suppression, Genetic
  • TATA-Binding Protein Associated Factors
  • Transcription Factor TFIID
  • Transcription, Genetic
  • Transcriptional Elongation Factors
  • mRNA Cleavage and Polyadenylation Factors