A novel CDK9-associated C-type cyclin interacts directly with HIV-1 Tat and mediates its high-affinity, loop-specific binding to TAR RNA.

The HIV-1 Tat protein regulates transcription elongation through binding to the viral TAR RNA stem-loop structure. We have isolated a novel 87 kDa cyclin C-related protein (cyclin T) that interacts specifically with the transactivation domain of Tat. Cyclin T is a partner for CDK9, an RNAPII transcription elongation factor. Remarkably, ...
the interaction of Tat with cyclin T strongly enhances the affinity and specificity of the Tat:TAR RNA interaction, and confers a requirement for sequences in the loop of TAR that are not recognized by Tat alone. Moreover, overexpression of human cyclin T rescues Tat activity in nonpermissive rodent cells. We propose that Tat directs cyclin T-CDK9 to RNAPII through cooperative binding to TAR RNA.
Mesh Terms:
3T3 Cells, Amino Acid Sequence, Animals, Bacterial Proteins, CHO Cells, Cell Nucleus, Chemoreceptor Cells, Cloning, Molecular, Cricetinae, Cyclin C, Cyclin T, Cyclin-Dependent Kinases, Cyclins, DNA Footprinting, Escherichia coli Proteins, Gene Expression Regulation, Viral, Gene Products, tat, HIV-1, Humans, Membrane Proteins, Mice, Molecular Sequence Data, Nucleic Acid Conformation, Positive Transcriptional Elongation Factor B, Protein-Serine-Threonine Kinases, RNA Polymerase II, RNA, Viral, Receptors, Cell Surface, Recombinant Proteins, Ribonucleases, Substrate Specificity, Transcription, Genetic, tat Gene Products, Human Immunodeficiency Virus
Cell
Date: Feb. 20, 1998
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