The RNA component of RNase P in Schizosaccharomyces species

In the fission yeast Schizosaccharomyces pombe, the enzyme RNAse P copurifies with two RNAs, K1- and K2-RNA, which are identical except for their termini [1] and which are encoded by a single gene [2]. We have undertaken the cloning of the K-RNA genes in related organisms in order to gain comparative structural information. Because the K-RNA sequence is poorly conserved across species, we have cloned the K-RNA genes in the Schizosaccharomyces species S. malidevorans, S. japonicus, S. versatilis, and S. octosporus. Of the 4 species, only S. octosporus contains a K-RNA gene different from that in S. pombe; the gene diverges by 20%. Based on the two sequences, nuclease protection data and computer analysis, we have proposed a secondary structure model for the K-RNA. Northern analysis shows the K-RNA genes in all four Schizosaccharomyces species to be expressed as two RNAs, as in S. pombe.