Modifications in host cell structure and functions mediated by Tat intracellular expression are greatly dependent on the second exon

Abstract

The human immunodeficiency virus type 1 (HIV-1) encodes the 110 amino acid-pleiotropic nuclear transcriptional activator Tat that is not only essential for efficient elongation of viral transcripts, but also regulates both cellular protein and gene expression. Tat encoding gene consists of two spliced exons separated in the HIV-1 genome by more than 2.300 nucleotides. First 72 residues at the N-terminal encoded by the first exon appear to be sufficient for transcriptional activity, but the integrity of the coding second exon in most lentiviral genomes suggests that it should have some biological importance. In this work, we demonstrate that the second exon completes Tat function.