Heat-shock inactivation of the TFIIH-associated kinase and change in the phosphorylation sites on the C-terminal domain of RNA polymerase II.
The C-terminal domain (CTD) of the RNA polymerase II largest subunit (RPB1) plays a central role in transcription. The CTD is unphosphorylated when the polymerase assembles into a preinitiation complex of transcription and becomes heavily phosphorylated during promoter clearance and entry into elongation of transcription. A kinase associated to the general transcription factor TFIIH, in the preinitiation complex, phosphorylates the CTD. The TFIIH-associated CTD kinase activity was found to decrease in extracts from heat-shocked HeLa cells compared to unstressed cells. This loss of activity correlated with a decreased solubility of the TFIIH factor. The TFIIH-kinase impairment during heat-shock was accompanied by the disappearance of a particular phosphoepitope (CC-3) on the RPB1 subunit. The CC-3 epitope was localized on the C-terminal end of the CTD and generated in vitro when the RPB1 subunit was phosphorylated by the TFIIH-associated kinase but not by another CTD kinase such as MAP kinase. In apparent discrepancy, the overall RPB1 subunit phosphorylation increased during heat-shock. The decreased activity in vivo of the TFIIH kinase might be compensated by a stress-activated CTD kinase such as MAP kinase. These results also suggest that heat-shock gene transcription may have a weak requirement for TFIIH kinase activity.
Dubois
M F
MF
Laboratoire de Génétique Moléculaire, URA CNRS 1302, Ecole Normale Supérieure, Paris, France.
Vincent
M
M
Vigneron
M
M
Adamczewski
J
J
Egly
J M
JM
Bensaude
O
O
D001666:Binding Sites, Antibody; D004789:Enzyme Activation; D006367:HeLa Cells; D006358:Hot Temperature; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000276:immunology / Q000378:metabolism*; D012319:RNA Polymerase II / Q000737:chemistry* / Q000378:metabolism*; D012995:Solubility; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000378:metabolism*; D019473:Transcription Factors, TFII
D014157:Transcription Factors; D019473:Transcription Factors, TFII; D051758:Transcription Factor TFIIH; D011494:Protein Kinases; C060137:carboxy-terminal domain kinase; D012319:RNA Polymerase II