RNA



Identification and functional analysis of hPRP17, the human homologue of the PRP17/CDC40 yeast gene involved in splicing and cell cycle control


SIGAL BEN  YEHUDA a1, IAN  DIX a2, CAROLINE S.  RUSSELL a2, SHARON  LEVY a3, JEAN D.  BEGGS a2 and MARTIN  KUPIEC a1c1
a1 Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
a2 Institute of Cell and Molecular Biology, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH93JR, United Kingdom
a3 Gesher Israel Advanced Biotecs, Beit Neqofa 90830, Israel

Abstract

The PRP17 gene of the yeast Saccharomyces cerevisiae encodes a protein that participates in the second step of the splicing reaction. It was found recently that the yeast PRP17 gene is identical to the cell division cycle CDC40 gene. The PRP17/CDC40 gene codes for a protein with several copies of the WD repeat, a motif found in a large family of proteins that play important roles in signal transduction, cell cycle progression, splicing, transcription, and development.

In this report, we describe the identification of human, nematode, and fission yeast homologues of the PRP17/CDC40 gene of S. cerevisiae. The newly identified proteins share homology with the budding yeast protein throughout their entire sequence, with the similarity being greatest in the C-terminal two thirds that includes the conserved WD repeats.

We show that a yeast–human chimera, carrying the C-terminal two thirds of the hPRP17 protein, is able to complement the cell cycle and splicing defects of a yeast prp17 mutant. Moreover, the yeast and yeast–human chimeric proteins co-precipitate the intron–exon 2 lariat intermediate and the intron lariat product, providing evidence that these proteins are spliceosome-associated. These results show the functional conservation of the Prp17 proteins in evolution and suggest that the second step of splicing takes place by a similar mechanism throughout eukaryotes.

(Received May 4 1998)
(Revised June 8 1998)
(Accepted July 22 1998)


Key Words: Prp17; spliceosome; splicing factor; WD motif.

Correspondence:
c1 Reprint requests to: Martin Kupiec, Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel; e-mail: martin@ccsg.tau.ac.il.