Nucleic Acids Research, Vol 25, Issue 8 1597-1604, Copyright © 1997 by Oxford University Press
LC Shaw and AS Lewin
The Cbp2 protein is encoded in the nucleus and is required for the splicing
of the terminal intron of the mitochondrial COB gene in Saccharomyces
cerevisiae . Using a yeast strain that lacks this intron but contains a
related group I intron in the precursor of the large ribosomal RNA, we have
determined that Cbp2 protein is also required for the normal accumulation
of 21S ribosomal RNA in vivo . Such strains bearing a deletion of the CBP2
gene adapt slowly to growth in glycerol/ethanol media implying a defect in
derepression. At physiologic concentrations of magnesium, Cbp2 stimulates
the splicing of the ribosomal RNA intron in vitro . Nevertheless, Cbp2 is
not essential for splicing of this intron in mitochondria nor is it
required in vitro at magnesium concentrations >5 mM. A similar intron
exists in the large ribosomal RNA (LSU) gene of Saccharomyces douglasii .
This intron does need Cbp2 for catalytic activity in physiologic magnesium.
Similarities between the LSU introns and COB intron 5 suggest that Cbp2 may
recognize conserved elements of the these two introns, and protein-induced
UV crosslinks occur in similar sites in the substrate and catalytic domains
of the RNA precursors.
ARTICLES
The Cbp2 protein stimulates the splicing of the omega intron of yeast mitochondria
Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Box 100266, Gainesville, FL 32610, USA.
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