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On how hydrolysis at the 3′ end is prevented in the splicing of a sequentially folded group I intron
Author(s) -
Fernández Ariel
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80360-s
Subject(s) - intron , exon , rna splicing , group ii intron , hydrolysis , chemistry , mutagenesis , sequence (biology) , messenger rna , genetics , biology , biochemistry , gene , mutation , rna
We propose a dynamic model for the competition between exon—exon ligation and 3′‐end hydrolysis valid for sequentially folded pre‐mRNA introns of group I. This model accounts for the delay in the formation of conserved helix P10 until the 5′ exon has been cleaved, a requirement to prevent hydrolysis at the 3′ end of the intron. The model is rooted on computer simulations whereby the pre‐mRNA searches for its structure as it is being transcribed. Thus, a competing interaction, engaging the internal guiding sequence, occurs initially and prevents P10 from forming until the 3′ end of the 5′ exon is habilitated as a nucleophilic agent. It is further shown that a destabilization of the competing interaction invariably leads to 3′ hydrolysis, crippling the splicing capability of the intron. The results may be probed by site‐directed mutagenesis.