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Partners of Rpb8p, a small subunit shared by yeast RNA polymerases I, II and III
J F Briand1, F Navarro, P Rematier
1Service de Biochimie and Génétique Moléculaire, CEA/Saclay, F-91191 Gif-sur-Yvette, France.
Molecular and Cellular Biology
|August 4, 2001
Summary
Rpb8p, a conserved RNA polymerase subunit, interacts with other subunits. Mutations in Rpb8p and its interaction with Rpa190p reveal functional connections, with Rpb6p suppressing defects and YGR089w potentially playing a role.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Rpb8p is a conserved subunit of all three yeast RNA polymerases, essential for eukaryotic transcription.
- Mutations in conserved motifs of Rpb8p affect its interaction with the pore 1 module of large RNA polymerase subunits.
Purpose of the Study:
- To investigate the functional interactions of Rpb8p with other RNA polymerase subunits.
- To elucidate the structural and functional significance of conserved motifs in Rpb8p and interacting partners.
Main Methods:
- Yeast genetics, including two-hybrid interaction assays and gene dosage suppression experiments.
- Analysis of temperature-sensitive mutants in RNA polymerase subunits.
- Structural analysis of conserved motifs and their spatial arrangement.
Main Results:
- Mutations in the GGLLM motif and other conserved residues of Rpb8p impair its interaction with the pore 1 module of Rpa190p, Rpb1p, and Rpc160p.
- A mutation in the P.I.KP.LW.GKQ motif of Rpa190p causes a temperature-sensitive defect suppressed by increased Rpb6p levels.
- Rpb6p suppresses defects in Rpb8p mutants and its human homolog, indicating functional interaction between Rpb6p and Rpb8p.
- Rpb8p interacts with the orphan gene product YGR089w, and its absence exacerbates rpb8 mutant phenotypes.
Conclusions:
- Rpb6p and Rpb8p functionally interact in vivo, potentially mediated through the pore 1 module and the N-terminal region of Rpb6p.
- The interaction between Rpb8p and YGR089w suggests a broader functional role for Rpb8p beyond core RNA polymerase function.