Functional domains required for tat-induced transcriptional activation of the HIV-1 long terminal repeat.
The transcriptional regulation of the human immunodeficiency virus (HIV) type I involves the interaction of both viral and cellular proteins. The viral protein tat is important in increasing the amount of viral steady-state mRNA and may also play a role in regulating the translational efficiency of viral mRNA. To identify distinct functional domains of tat, oligonucleotide-directed mutagenesis of the tat gene was performed. Point mutations of cysteine residues in three of the four Cys-X-X-Cys sequences in the tat protein resulted in a marked decrease in transcriptional activation of the HIV long terminal repeat. Point mutations which altered the basic C-domain of the protein also resulted in decreases in transcriptional activity, as did a series of mutations that repositioned either the N or C termini of the protein. Conservative mutations of other amino acids in the cysteine-rich or basic regions and in a series of proline residues in the N terminus of the molecule resulted in minimal changes in tat activation. These results suggest that several domains of tat protein are involved in transcriptional activation with the cysteine-rich domain being required for complete activity of the tat protein.
Garcia
J A
JA
Department of Medicine, UCLA School of Medicine 90024.
Harrich
D
D
Pearson
L
L
Mitsuyasu
R
R
Gaynor
R B
RB
D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D006678:HIV / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D012191:Retroviridae Proteins / Q000235:genetics*; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D012191:Retroviridae Proteins; D014157:Transcription Factors