title: Insights into the selective activation of alternatively used splice acceptors by the human immunodeficiency virus type-1 bidirectional splicing enhancer.
abstract: The guanosine-adenosine-rich exonic splicing enhancer (GAR ESE) identified in exon 5 of the human immunodeficiency virus type-1 (HIV-1) pre-mRNA activates either an enhancer-dependent 5' splice site (ss) or 3' ss in 1-intron reporter constructs in the presence of the SR proteins SF2/ASF2 and SRp40. Characterizing the mode of action of the GAR ESE inside the internal HIV-1 exon 5 we found that this enhancer fulfils a dual splicing regulatory function (i) by synergistically mediating exon recognition through its individual SR protein-binding sites and (ii) by conferring 3' ss selectivity within the 3' ss cluster preceding exon 5. Both functions depend upon the GAR ESE, U1 snRNP binding at the downstream 5' ss D4 and the E42 sequence located between these elements. Therefore, a network of cross-exon interactions appears to regulate splicing of the alternative exons 4a and 5. As the GAR ESE-mediated activation of the upstream 3' ss cluster also is essential for the processing of intron-containing vpu/env-mRNAs during intermediate viral gene expression, the GAR enhancer substantially contributes to the regulation of viral replication.
authors.affiliation: Institut für Virologie, Universitätsklinikum Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany.
authors.forename: Corinna
authors.initials: C
authors.lastname: Asang
authors.forename: Ilona
authors.initials: I
authors.lastname: Hauber
authors.forename: Heiner
authors.initials: H
authors.lastname: Schaal
mesh_terms: D000241:Adenosine / Q000032:analysis; D017398:Alternative Splicing; D001665:Binding Sites; D005091:Exons; D006151:Guanosine / Q000032:analysis; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D009687:Nuclear Proteins / Q000378:metabolism; D012322:RNA Precursors / Q000737:chemistry; D022821:RNA Splice Sites; D012333:RNA, Messenger / Q000737:chemistry; D012367:RNA, Viral / Q000737:chemistry*; D016601:RNA-Binding Proteins; D038621:Regulatory Sequences, Ribonucleic Acid; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D054321:rev Gene Products, Human Immunodeficiency Virus / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D012322:RNA Precursors; D022821:RNA Splice Sites; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D038621:Regulatory Sequences, Ribonucleic Acid; D017412:Ribonucleoprotein, U1 Small Nuclear; D054321:rev Gene Products, Human Immunodeficiency Virus; C514860:rev protein, Human Immunodeficiency Virus-1; D006151:Guanosine; D000068103:Serine-Arginine Splicing Factors; D000241:Adenosine