Functional domains of Tat required for efficient human immunodeficiency virus type 1 reverse transcription.
Tat expression is required for efficient human immunodeficiency virus type 1 (HIV-1) reverse transcription. In the present study, we generated a series of 293 cell lines that contained a provirus with a tat gene deletion (Deltatat). Cell lines that contained Deltatat and stably transfected vectors containing either wild-type tat or a number of tat mutants were obtained so that the abilities of these tat genes to stimulate HIV-1 gene expression and reverse transcription could be compared. tat genes with mutations in the amino terminus did not stimulate either viral gene expression or HIV-1 reverse transcription. In contrast, tat mutants in the activation, core, and basic domains of Tat did not stimulate HIV-1 gene expression but markedly stimulated HIV-1 reverse transcription. No differences in the levels of virion genomic RNA or tRNA3Lys were seen in the HIV-1 Deltatat viruses complemented with either mutant or wild-type tat. Finally, overexpression of the Tat-associated kinases CDK7 and CDK9, which are involved in Tat activation of HIV-1 transcription, was not able to complement the reverse transcription defects associated with the lack of a functional tat gene. These results indicate that the mechanism by which tat modulates HIV-1 reverse transcription is distinct from its ability to activate HIV-1 gene expression.
Ulich
C
C
Division of Hematology and Oncology, Departments of Internal Medicine and Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-8594, USA.
Dunne
A
A
Parry
E
E
Hooker
C W
CW
Gaynor
R B
RB
Harrich
D
D
D000595:Amino Acid Sequence; D018844:Cyclin-Dependent Kinases; D015696:Gene Products, tat / Q000737:chemistry / Q000502:physiology*; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D012367:RNA, Viral / Q000032:analysis; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic; D014162:Transfection; D014771:Virion / Q000235:genetics; D054322:tat Gene Products, Human Immunodeficiency Virus; D000095043:Cyclin-Dependent Kinase-Activating Kinase