Rpa12p, a conserved RNA polymerase I subunit with two functional domains.
Rpa12p is a subunit of RNA polymerase I formed of two zinc-binding domains. The N-terminal zinc region (positions 1-60) is poorly conserved from yeast to man. The C-terminal domain contains an invariant Q.RSADE.T.F motif shared with the TFIIS elongation factor of RNA polymerase II and its archaeal counterpart. Deletions removing the N-terminal domain fail to grow at 34 degrees C, are sensitive to nucleotide-depleting drugs and become lethal in rpa14-Delta mutants lacking the non-essential RNA polymerase I subunit Rpa14p. They also strongly alter the immunofluorescent properties of RNA polymerase I in the nucleolus. Finally, they prevent the binding of Rpa12p to immunopurified polymerase I and impair a specific two-hybrid interaction with the second largest subunit. In all these respects, N-terminal deletions behave like full deletions. In contrast, C-terminal deletions retaining only the first N-terminal 60 amino acids are indistinguishable from wild type. Thus, the N-terminal zinc domain of Rpa12p determines its anchoring to RNA polymerase I and is the only critical part of that subunit in vivo.
Van Mullem
Vincent
V
Laboratoire de Génétique Moléculaire, URBM, Facultés Universitaires Notre-Dame de la Paix, 61 rue de Bruxelles, B-5000 Namur, Belgium.
Landrieux
Emilie
E
Vandenhaute
Jean
J
Thuriaux
Pierre
P
D000595:Amino Acid Sequence; D017124:Conserved Sequence; D003470:Culture Media; D017353:Gene Deletion; D008969:Molecular Sequence Data; D012318:RNA Polymerase I / Q000737:chemistry* / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000502:physiology*; D020798:Two-Hybrid System Techniques
D003470:Culture Media; D029701:Saccharomyces cerevisiae Proteins; C423311:RPA12 protein, S cerevisiae; D012318:RNA Polymerase I