Mechanism of recognition of the 5' splice site in self-splicing group I introns

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摘要：

Group I introns include many mitochondrial ribosomal RNA and messenger RNA introns and the nuclear rRNA introns of Tetrahymena and Physarum 1–6 . The splicing of precursor RNAs containing these introns is a two-step reaction. Cleavage at the 5′ splice site precedes cleavage at the 3′ splice site, the latter cleavage being coupled with exon ligation 7–9 . Following the first cleavage, the 5′ exon must somehow be held in place for ligation. We have now tested the reactivity of two self-splicing group I RNAs, the Tetrahymena pre-rRNA and the intron 1 portion of the Neurospora mitochondrial cytochrome b ( cob ) pre-mRNA, in the inter-molecular exon ligation reaction (splicing in trans ) described by Inoue et al. 10 . The different sequence specificity of the reactions supports the idea that the nucleotides immediately upstream from the 5′ splice site are base-paired to an internal, 5′ exon-binding site, in agreement with RNA structure models proposed by Davies and co-workers 2,3 and others 4,5,11 . The internal binding site is proposed to be involved in the formation of a structure that specifies the 5′ splice site and, following the first step of splicing, to hold the 5′ exon in place for exon ligation.

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DOI：

10.1038/322086a0

被引量：

888

年份：

1986