Open AccessAn intronic (A/U)GGG repeat enhances the splicing of an alternative intron of the chicken β-tropomyosin pre-mRNA
Author(s) -
Pascal SirandPugnet,
Patrice Durosay,
Edward N. Brody,
Joëlle Marie
Publication year - 1995
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/23.17.3501
Subject(s) - spliceosome , biology , rna splicing , intron , snrnp , sr protein , exonic splicing enhancer , precursor mrna , polypyrimidine tract , enhancer , genetics , microbiology and biotechnology , ribonucleoprotein , exon , small nuclear rna , minor spliceosome , rna , gene , gene expression , non coding rna
Computer analysis of human intron sequences have revealed a 50 nucleotide (nt) GC-rich region downstream of the 5' splice site; the trinucleotide GGG occurs almost four times as frequently as it would in a random sequence. The 5' part of a beta-tropomyosin intron exhibits six repetitions of the motif (A/U)GGG. In order to test whether these motifs play a role in the splicing process we have mutated some or all of them. Mutated RNAs show a lower in vitro splicing efficiency when compared with the wild-type, especially when all six motifs are mutated (> 70% inhibition). Assembly of the spliceosome complex B and, to a lesser extent, of the pre-spliceosome complex A also appears to be strongly affected by this mutation. A 55 kDa protein within HeLa cell nuclear extract is efficiently cross-linked to the G-rich region. This protein is present in the splicing complexes and its cross-linking to the pre-mRNA requires the presence of one or several snRNP. Altogether our results suggest that the G-rich sequences present in the 5' part of introns may act as an enhancer of the splicing reaction at the level of spliceosome assembly.