The fission yeast rpa17 super(+) gene encodes a functional homolog of AC19, a subunit of RNA polymerases I and III of Saccharomyces cerevisiae

• Published in: Molecular & general genetics Vol. 261; no. 2; pp. 364 - 373
• Main Authors: Imai, K, Imazawa, Y, Yao, Y, Yamamoto, K, Hisatake, K, Muramatsu, M, Nogi, Y
• Format: Journal Article
• Language: English
• Published: 02.03.1999
• Subjects: Saccharomyces cerevisiae; Schizosaccharomyces pombe
• ISSN: 0026-8925

Eukaryotic RNA polymerases I and III consist of multiple subunits. Each of these enzymes includes two distinct and evolutionarily conserved subunits called -related subunits which are shared only by polymerases I and III. The -related subunits show limited homology with the -subunit of prokaryotic RNA polymerase. To gain further insight into the structure and function of -related subunits, we cloned and characterized a gene from Schizosaccharomyces pombe that encodes a protein of 17 kDa which can functionally replace AC19 - an -related subunit of RNA polymerases I and III of Saccharomyces cerevisiae - and was thus named rpa17 super(+). RPA17 has 125 amino acids and shows 63% identity to AC19 over a 108-residue stretch, whereas the N-terminal regions of the two proteins are highly divergent. Disruption of rpa17 super(+) shows that the gene is essential for cell growth. Sequence comparison with other -related subunits from different species showed that RPA17 contains an 81-amino acid block that is evolutionarily conserved. Deletion analysis of the N- and C-terminal regions of RPA17 and AC19 confirms that the 81-amino acid block is important for the function of the -related subunits.