TFIIH inhibits CDK9 phosphorylation during human immunodeficiency virus type 1 transcription.
Tat stimulates human immunodeficiency virus, type 1 (HIV-1), transcription elongation by recruitment of the human transcription elongation factor P-TEFb, consisting of CDK9 and cyclin T1, to the TAR RNA structure. It has been demonstrated further that CDK9 phosphorylation is required for high affinity binding of Tat/P-TEFb to the TAR RNA structure and that the state of P-TEFb phosphorylation may regulate Tat transactivation. We now demonstrate that CDK9 phosphorylation is uniquely regulated in the HIV-1 preinitiation and elongation complexes. The presence of TFIIH in the HIV-1 preinitiation complex inhibits CDK9 phosphorylation. As TFIIH is released from the elongation complex between +14 and +36, CDK9 phosphorylation is observed. In contrast to the activity in the "soluble" complex, phosphorylation of CDK9 is increased by the presence of Tat in the transcription complexes. Consistent with these observations, we have demonstrated that purified TFIIH directly inhibits CDK9 autophosphorylation. By using recombinant TFIIH subcomplexes, our results suggest that the XPB subunit of TFIIH is responsible for this inhibition of CDK9 phosphorylation. Interestingly, our results further suggest that the phosphorylated form of CDK9 is the active kinase for RNA polymerase II carboxyl-terminal domain phosphorylation.
Zhou
M
M
Virus Tumor Biology Section, Basic Research Laboratory, Division of Basic Sciences, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Nekhai
S
S
Bharucha
D C
DC
Kumar
A
A
Ge
H
H
Price
D H
DH
Egly
J M
JM
Brady
J N
JN
D015153:Blotting, Western; D042863:Cyclin-Dependent Kinase 9; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D015696:Gene Products, tat / Q000378:metabolism; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008954:Models, Biological; D010766:Phosphorylation; D042925:Positive Transcriptional Elongation Factor B; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000378:metabolism*; D019473:Transcription Factors, TFII; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus; D000095043:Cyclin-Dependent Kinase-Activating Kinase
D015696:Gene Products, tat; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D054322:tat Gene Products, Human Immunodeficiency Virus; D051758:Transcription Factor TFIIH; D012694:Serine; D012313:RNA; D042925:Positive Transcriptional Elongation Factor B; D017346:Protein Serine-Threonine Kinases; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9; D018844:Cyclin-Dependent Kinases; D012319:RNA Polymerase II; D000095043:Cyclin-Dependent Kinase-Activating Kinase