Molecular Cloning and Characterization of cDNA of the rpc10⁺ Gene Encoding the Smallest Subunit of Nuclear RNA Polymerases of Schizosaccharomyces pombe

The full-length cDNA of the rpc10⁺ gene encoding mini-subunit Rpc10, which is common for all three nuclear RNA polymerases of the fission yeast Schizosaccharomyces pombe, was cloned and sequenced. The Rpc10 subunit of Sz. pombe and its homologs from S. cerevisiae and H. sapiens are positively charged proteins with a highly conserved C-terminal region and an invariant zinc-binding domain (Zn-finger) of a typical amino acid composition: YxCx₂Cx₁₂RCx₂CGxR. Functional tests on heterospecific complementation, using tetrad analysis or plasmid shuffling, showed that the Rpc10 subunit of Sz. pombe can successfully replace the homologous ABC10α subunit in nuclear RNA polymerases I-III of S. cerevisiae.