RNA



The identification and characterization of a novel splicing protein, Isy1p, of Saccharomyces cerevisiae


IAN  DIX a1, CAROLINE  RUSSELL a1, SIGAL  BEN YEHUDA a2, MARTIN  KUPIEC a2 and JEAN D.  BEGGS a1c1
a1 Institute of Cell and Molecular Biology, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, United Kingdom
a2 Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, 69978, Israel

Abstract

We have identified a novel splicing factor, Isy1p, through two-hybrid screens for interacting proteins involved in nuclear pre-mRNA splicing. Isy1p was tagged and demonstrated to be part of the splicing machinery, associated with spliceosomes throughout the splicing reactions. At least a portion of the Isy1 protein population is associated with snRNAs; low levels of U5 and U6 snRNAs are coimmunoprecipitated specifically with Isy1p. When the ISY1 gene was knocked out, no defect in vegetative growth was observed. Using a sensitive in vivo splicing assay, however, we observed lower splicing efficiency in the isy1 null mutant compared to wild-type, indicating that Isy1p is important in the optimization of splicing.

(Received August 17 1998)
(Revised September 10 1998)
(Accepted November 23 1998)


Key Words: pre-mRNA splicing; snRNA; snRNPs; spliceosome; yeast.

Correspondence:
c1 Reprint requests to: Jean D. Beggs, Institute of Cell and Molecular Biology, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, United Kingdom; e-mail: jbeggs@ed.ac.uk.