COTRANSCRIPTIONAL SPLICING OF A GROUP-I INTRON IS FACILITATED BY THE CBP2 PROTEIN

Citation
As. Lewin et al., COTRANSCRIPTIONAL SPLICING OF A GROUP-I INTRON IS FACILITATED BY THE CBP2 PROTEIN, Molecular and cellular biology, 15(12), 1995, pp. 6971-6978
Citations number
66
Categorie Soggetti
Biology
ISSN journal
02707306
Volume
15
Issue
12
Year of publication
1995
Pages
6971 - 6978
Database
ISI
SICI code
0270-7306(1995)15:12<6971:CSOAGI>2.0.ZU;2-H
Abstract
The nuclear CBP2 gene encodes a protein essential for the splicing of a mitochondrial group I intron in Saccharomyces cerevisiae. This intro n (bI5) is spliced autocatalytically in the presence of high concentra tions of magnesium and monovalent salt but requires the Cbp2 protein f or splicing under physiological conditions. Addition of Cbp2 during RN A synthesis permitted cotranscriptional splicing. Splicing did not occ ur in the transcription buffer in the absence of synthesis. The Cbp2 p rotein appeared to modify the folding of the intron during RNA synthes is: pause sites for RNA polymerase were altered in the presence of the protein, and some mutant transcripts that did not splice after transc ription did so during transcription in the presence of Cbp2. Cotranscr iptional splicing also reduced hydrolysis at the 3' splice junction. T hese results suggest that Cbp2 modulates the sequential folding of the ribozyme during its synthesis. In addition, splicing during transcrip tion led to an increase in RNA synthesis with both T7 RNA polymerase a nd mitochondrial RNA polymerase, implying a functional coupling betwee n transcription and splicing.