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T-loop phosphorylation stabilizes the CDK7-cyclin H-MAT1 complex in vivo and regulates its CTD kinase activity.

Authors :
Larochelle S
Chen J
Knights R
Pandur J
Morcillo P
Erdjument-Bromage H
Tempst P
Suter B
Fisher RP
Source :
The EMBO journal [EMBO J] 2001 Jul 16; Vol. 20 (14), pp. 3749-59.
Publication Year :
2001

Abstract

Cyclin-dependent kinase (CDK)7-cyclin H, the CDK-activating kinase (CAK) and TFIIH-associated kinase in metazoans can be activated in vitro through T-loop phosphorylation or binding to the RING finger protein MAT1. Although the two mechanisms can operate independently, we show that in a physiological setting, MAT1 binding and T-loop phosphorylation cooperate to stabilize the CAK complex of Drosophila. CDK7 forms a stable complex with cyclin H and MAT1 in vivo only when phosphorylated on either one of two residues (Ser164 or Thr170) in its T-loop. Mutation of both phosphorylation sites causes temperature-dependent dissociation of CDK7 complexes and lethality. Furthermore, phosphorylation of Thr170 greatly stimulates the activity of the CDK7- cyclin H-MAT1 complex towards the C-terminal domain of RNA polymerase II without significantly affecting activity towards CDK2. Remarkably, the substrate-specific increase in activity caused by T-loop phosphorylation is due entirely to accelerated enzyme turnover. Thus phosphorylation on Thr170 could provide a mechanism to augment CTD phosphorylation by TFIIH-associated CDK7, and thereby regulate transcription.

Details

Language :
English
ISSN :
0261-4189
Volume :
20
Issue :
14
Database :
MEDLINE
Journal :
The EMBO journal
Publication Type :
Academic Journal
Accession number :
11447116
Full Text :
https://doi.org/10.1093/emboj/20.14.3749