The fission yeast rpa17+ gene encodes a functional homolog of AC19, a subunit of RNA polymerases I and III of Saccharomyces cerevisiae.
Eukaryotic RNA polymerases I and III consist of multiple subunits. Each of these enzymes includes two distinct and evolutionarily conserved subunits called alpha-related subunits which are shared only by polymerases I and III. The alpha-related subunits show limited homology with the alpha-subunit of prokaryotic RNA polymerase. To gain further insight into the structure and function of alpha-related subunits, we cloned and characterized a gene from Schizosaccharomyces pombe that encodes a protein of 17 kDa which can functionally replace AC19 - an alpha-related subunit of RNA polymerases I and III of Saccharomyces cerevisiae - and was thus named rpa17+. 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+ shows that the gene is essential for cell growth. Sequence comparison with other alpha-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 alpha-related subunits.
Imai
K
K
Department of Biochemistry, Saitama Medical School, Iruma-Gun, Japan.
Imazawa
Y
Y
Yao
Y
Y
Yamamoto
K
K
Hisatake
K
K
Muramatsu
M
M
Nogi
Y
Y
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004271:DNA, Fungal; D012321:DNA-Directed RNA Polymerases; D005057:Eukaryotic Cells; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011506:Proteins / Q000235:genetics*; D012318:RNA Polymerase I / Q000235:genetics*; D012320:RNA Polymerase III / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins
D004271:DNA, Fungal; D011506:Proteins; D029702:Schizosaccharomyces pombe Proteins; C118430:rpc19 protein, S pombe; D012321:DNA-Directed RNA Polymerases; D012318:RNA Polymerase I; D012320:RNA Polymerase III