The fission yeast RPA51 is a functional homolog of the budding yeast A49 subunit of RNA polymerase I and required for maximizing transcription of ribosomal DNA.
Saccharomyces cerevisiae A49 and mouse PAF53 are subunits specific to RNA polymerase I (Pol I) in eukaryotes. It has been known that Pol I without A49 or PAF53 maintains non-specific transcription activities but a molecular role(s) of A49 (and PAF53) remains totally unknown. We studied the fission yeast gene encoding a protein of 415 amino acids exhibiting 30% and 19% identities to A49 and PAF53, respectively. We designate the corresponding protein RPA51 and gene encoding it rpa51+ since the gene encodes a Pol I subunit and an apparent molecular mass of the protein is 51 kDa. rpa51+ is required for cell growth at lower but not at higher temperatures and is able to complement S. cerevisiae rpa49Delta mutation, indicating that RPA51 is a functionally-conserved subunit of Pol I between the budding yeast and the fission yeast. Deletion analysis of rpa51+ shows that only two-thirds of the C-terminal region are required for the function. Transcripts analysis in vivo and in vitro shows that RPA51 plays a general role for maximizing transcription of rDNA whereas it is dispensable for non-specific transcription. We also found that RPA51 associates significantly with Pol I in the stationary phase, suggesting that Pol I inactivation in the stationary phase of yeast does not result from the RPA51 dissociation.
Nakagawa
Kaori
K
Department of Molecular Biology, Saitama Medical School, Iruma-Gun, Saitama, Japan.
Hisatake
Koji
K
Imazawa
Yukiko
Y
Ishiguro
Akira
A
Matsumoto
Masahito
M
Pape
Louise
L
Ishihama
Akira
A
Nogi
Yasuhisa
Y
D000595:Amino Acid Sequence; D004275:DNA, Ribosomal / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D012318:RNA Polymerase I / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D004718:Saccharomycetales / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D004275:DNA, Ribosomal; D021122:Protein Subunits; D012318:RNA Polymerase I