Rna14p, a component of the yeast nuclear Cleavage/Polyadenylation Factor I, is also localised in mitochondria

RNA14 was identified as a gene involved in premessenger RNA cleavage and po lyadenylation. These processing steps take place in the nucleus, but the Rn a14p protein is distributed in both the nucleus and the cytoplasm. By subce llular fractionation, we show here that the cytoplasmic fraction is localis ed in the mitochondria. In order to understand the role played by Rna14p in mitochondria, we have searched fbr new thermosensitive alleles of RNA14. W e isolated thirteen new mutants. Some of them are deficient in mRNA cleavag e and polyadenylation at the restrictive temperature - like the first mutan t identified (rna14-1). However, others do not appear to be impaired in any of the steps in RNA metabolism investigated, nor do they appear to be invo lved in the replication or expression of mitochondrial,DNA or in respiratio n. The localisation data strongly suggest that, besides an essential functi on in mRNA polyadenylation, the Rna14p protein has a non essential function in mitochondrial metabolism.