TAT AND THE HIV-1 PROMOTER - A MODEL FOR RNA-MEDIATED REGULATION OF TRANSCRIPTION

The human immunodeficiency virus (HIV-1) promoter is unique among RNA pol II transcription units in that it contains an element in the leader RNA (the trans-activation response element, or TAR) which regulates transcriptional induction by the virus-encoded regulatory protein, Tat. Tat acts through the TAR element to increase the efficiency of RNA transcript elongation, and under selected circumstances is also capable of enhancing the RNA initiation rate. Transcripts that initiate in the absence of Tat are elongated inefficiently and terminate at random, a process that we will refer to as attenuation. In this review, we consider the mechanism of trans-activation by Tat (including the role of TAR RNA) as well as the influence of host cell DNAbinding proteins on the assembly of productive and abortive transcription complexes at the HIV-1 promoter. © 1993 Academic Press Ltd.