Base pairing at the 5' splice site with U1 small nuclear RNA promotes splicing of the upstream intron but may be dispensable for slicing of the downstream intron.
AUTOR(ES)
Hwang, D Y
RESUMO
We previously reported that exon skipping in vivo due to point mutations in the 5' splice site (5'ss) signal of an internal mammalian exon can be prevented by coexpression of U1 small nuclear RNAs, termed shift-U1s, with complementarity to sequence upstream or downstream of the mutated site. We now show by S1 nuclease protection experiments that a typical shift-U1 restores splicing of the upstream intron, but not necessarily of the down stream intron. This indicates that the normal 5'ss sequence acts as an enhancer for splicing of the upstream intron, that it owes this activity to base pairing with U1, and that the enhancer activity is reproduced by base pairing of U1 with other sequences in the area. Shift-U1s are dispensable when the 3'ss sequence of the upstream intron is improved, which suggests that base pairing of U1 with sequences at or near the downstream end of the exon normally functions by compensating for a weakness in the upstream 3'ss. Accordingly, U1 appears to be involved in communication across the exon, but our data indicate at the same time that extensive base pairing between U1 and the 5'ss sequence is not necessary for accurate splicing of the downstream intron. These findings are discussed in relation to the coordinate selection exon termini proposed by the exon definition model.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=231296Documentos Relacionados
- The Pre-mRNA 5′ Cap Determines Whether U6 Small Nuclear RNA Succeeds U1 Small Nuclear Ribonucleoprotein Particle at 5′ Splice Sites
- Evidence for a base-pairing interaction between U6 small nuclear RNA and 5' splice site during the splicing reaction in yeast.
- Effect of 5' splice site mutations on splicing of the preceding intron.
- In vitro splicing of mRNA precursors: 5' cleavage site can be predicted from the interaction between the 5' splice region and the 5' terminus of U1 snRNA.
- Suppression of mammalian 5' splice-site defects by U1 small nuclear RNAs from a distance.
