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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Fong, Y. Zhou, Q. Chen, D. |
| Description | Author Affiliation: Chen D ( Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3206, USA.); |
| Abstract | Tat stimulation of HIV-1 transcriptional elongation is species-specific and is believed to require a specific cellular cofactor present in many human and primate cells but not in nonpermissive rodent cells. Human P-TEFb, composed of Cdk9 and cyclin T1, is a general transcription elongation factor that phosphorylates the C-terminal domain of RNA polymerase II. Previous studies have also implicated P-TEFb as a Tat-specific cellular cofactor and, in particular, human cyclin T1 as responsible for the species-specific Tat activation. To obtain functional evidence in support of these hypotheses, we generated and examined the activities of human-rodent 'hybrid' P-TEFb complexes. We found that P-TEFb complexes containing human cyclin T1 complexed with either human or rodent Cdk9 supported Tat transactivation and interacted with the Tat activation domain and the HIV-1 TAR RNA element to form TAR loop-dependent ribonucleoprotein complexes. Although a stable complex containing rodent cyclin T1 and human Cdk9 was capable of phosphorylating CTD and mediating basal HIV-1 elongation, it failed to interact with Tat and to mediate Tat transactivation, indicating that the abilities of P-TEFb to support basal elongation and Tat activation can be separated. Together, our data indicated that the specific interaction of human P-TEFb with Tat/TAR, mostly through cyclin T1, is crucial for P-TEFb to mediate a Tat-specific and species-restricted activation of HIV-1 transcription. Amino acid residues unique to human Cdk9 also contributed partially to the formation of the P-TEFb-Tat-TAR complex. Moreover, the cyclin box of cyclin T1 and its immediate flanking region are largely responsible for the specific P-TEFb-Tat interaction. |
| ISSN | 00278424 |
| e-ISSN | 10916490 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Issue Number | 6 |
| Volume Number | 96 |
| Language | English |
| Publisher | National Academy of Sciences |
| Publisher Date | 1999-05-01 |
| Publisher Place | United States |
| Access Restriction | Open |
| Subject Keyword | Gene Products, Tat Genetics HIV-1 Physiology Protein-Serine-Threonine Kinases Virus Replication Animals Gene Expression Regulation, Viral Metabolism Phosphorylation Positive Transcriptional Elongation Factor B Rodentia Species Specificity Transcription, Genetic Tat Gene Products, Human Immunodeficiency Virus Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Research Support, U.S. Gov't, P.H.S. Multidisciplinary |
| Content Type | Text |
| Resource Type | Article |
| Subject | Multidisciplinary |
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