Format

Send to:

Choose Destination
See comment in PubMed Commons below
Mol Cell Biol. 2012 Jul;32(13):2372-83. doi: 10.1128/MCB.06657-11. Epub 2012 Apr 16.

Separate domains of fission yeast Cdk9 (P-TEFb) are required for capping enzyme recruitment and primed (Ser7-phosphorylated) Rpb1 carboxyl-terminal domain substrate recognition.

Author information

  • 1Department of Structural and Chemical Biology, Mount Sinai School of Medicine, New York, New York, USA.

Abstract

In fission yeast, discrete steps in mRNA maturation and synthesis depend on a complex containing the 5'-cap methyltransferase Pcm1 and Cdk9, which phosphorylates the RNA polymerase II (Pol II) carboxyl-terminal domain (CTD) and the processivity factor Spt5 to promote transcript elongation. Here we show that a Cdk9 carboxyl-terminal extension, distinct from the catalytic domain, mediates binding to both Pcm1 and the Pol II CTD. Removal of this segment diminishes Cdk9/Pcm1 chromatin recruitment and Spt5 phosphorylation in vivo and leads to slow growth and hypersensitivity to cold temperature, nutrient limitation, and the IMP dehydrogenase inhibitor mycophenolic acid (MPA). These phenotypes, and the Spt5 phosphorylation defect, are suppressed by Pcm1 overproduction, suggesting that normal transcript elongation and gene expression depend on physical linkage between Cdk9 and Pcm1. The extension is dispensable, however, for recognition of CTD substrates "primed" by Mcs6 (Cdk7). On defined peptide substrates in vitro, Cdk9 prefers CTD repeats phosphorylated at Ser7 over unmodified repeats. In vivo, Ser7 phosphorylation depends on Mcs6 activity, suggesting a conserved mechanism, independent of chromatin recruitment, to order transcriptional CDK functions. Therefore, fission yeast Cdk9 comprises a catalytic domain sufficient for primed substrate recognition and a multivalent recruitment module that couples transcription with capping.

PMID:
22508988
[PubMed - indexed for MEDLINE]
PMCID:
PMC3434489
Free PMC Article

Publication Types, MeSH Terms, Substances, Grant Support

Publication Types

MeSH Terms

Substances

Grant Support

PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk