The D1-A2 and D2-A2 pairs of splice sites from human immunodeficiency virus type 1 are highly efficient in vitro, in spite of an unusual branch site.
Using in vitro splicing assays with HeLa cell nuclear extracts, we showed that the HIV-1 pairs of splice sites D1-A2 and D2-A2 are efficiently used in vitro, as compared to the control D1-A2 pair of sites from the E3 transcription unit of human adenovirus-2. The strong efficiency of the two HIV-1 pairs of sites is surprising, as we also showed by primer extension analysis that the branch-site sequence used at the HIV-1 acceptor site A2 is UAGCAGA, with a dominant utilization of the ultimate G as the branched residue. No significant increase of the splicing efficiency was observed upon replacement of the wild-type branch-site sequence by a canonical sequence, in spite of the utilization of an A residue as the branched nucleotide. Results are discussed taking into account the present knowledge on branch-site selection.
Damier
L
L
Laboratoire d'Enzymologie et de Genie Génétique, URA CNRS 457, Université Henri Poincaré Nancy 1, Vandoeuvre les Nancy, France.
Domenjoud
L
L
Branlant
C
C
D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D016384:Consensus Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D056890:Eukaryota / Q000235:genetics; D005091:Exons; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D016133:Polymerase Chain Reaction; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000737:chemistry; D012367:RNA, Viral / Q000096:biosynthesis*; D014158:Transcription, Genetic
D017931:DNA Primers; D018076:DNA, Complementary; D012342:RNA, Small Nuclear; D012367:RNA, Viral