Transcription of the HIV genome Authored: Matthews, L, Rice, AP, 2005-07-27 00:00:00 Edited: Matthews, L, 2005-07-26 23:29:22 Expression of the integrated HIV-1 provirus is dependent on the host cell Pol II transcription machinery, but is regulated in critical ways by HIV-1 Tat and Rev proteins. The long terminal repeats (LTR) located at either end of the proviral DNA contain regulatory sequences that recruit cellular transcription factors. The U3 region of the 5' LTR contains numerous cis-acting elements that regulate Pol II-mediated transcription initiation. The full-length transcript, which encodes nine genes, functions as an mRNA and is packaged as genomic RNA. Smaller (subgenomic) viral mRNAs are generated by alternative splicing. The activities of Tat and Rev create two phases of gene expression (see Karn 1999; Cullen 1991). The Tat protein is an RNA specific trans-activator of LTR-mediated transcription. Association of Tat with TAR, a RNA stem-loop within the RNA leader sequence, is required for efficient elongation of the HIV-1 transcript. In the early phase of viral transcription, a multiply-spliced set of mRNAs is generated, producing the transcripts of the regulatory proteins, Tat, Rev, and Nef. In the late phase, Rev regulates nuclear export of HIV-1 mRNAs, repressing expression of the early regulatory mRNAs and promoting expression of viral structural proteins. Nuclear export of the unspliced and partially spliced late HIV-1 transcripts that encode the structural proteins requires the association of Rev with a cis-acting RNA sequence in the transcripts (Rev Response Element, RRE). GENE ONTOLOGYGO:0019083 Pubmed10550206 Pubmed1995941 Pubmed9791012 Reactome Database ID Release 43167172 Reactome, http://www.reactome.org ReactomeREACT_6233 Reviewed: Peterlin, BM, 2005-01-05 00:00:00 HIV-1 Transcription Initiation RNA Polymerase II HIV-1 Promoter Escape RNA Pol II CTD phosphorylation and interaction with CE HIV-1 Transcription Elongation Formation of HIV-1 elongation complex in the absence of HIV-1 Tat HIV-1 elongation arrest and recovery Pausing and recovery of Tat-mediated HIV-1 elongation HIV-1 Transcription Termination Pausing and recovery of HIV-1 elongation Tat-mediated HIV-1 elongation arrest and recovery PathwayStep3556 PathwayStep3550 PathwayStep3536 PathwayStep3537 PathwayStep3542 HIV-1 Promoter Opening: First Transition Fall Back to Closed Pre-initiation Complex PathwayStep3580 PathwayStep3586 PathwayStep3583 PathwayStep3576 PathwayStep3590 PathwayStep3593 PathwayStep3594