Site specific phosphorylation of yeast RNA polymerase I.
All nuclear RNA polymerases are phosphoprotein complexes. Yeast RNA polymerase I (Pol I) contains approximately 15 phosphate groups, distributed to 5 of the 14 subunits. Information about the function of the single phosphosites and their position in the primary, secondary and tertiary structure is lacking. We used a rapid and ... efficient way to purify yeast RNA Pol I to determine 13 phosphoserines and -threonines. Seven of these phosphoresidues could be located in the 3D-homology model for Pol I, five of them are more at the surface. The single phosphorylated residues were systematically mutated and the resulting strains and Pol I preparations were analyzed in cellular growth, Pol I composition, stability and genetic interaction with non-essential components of the transcription machinery. Surprisingly, all Pol I phosphorylations analyzed were found to be non-essential post-translational modifications. However, one mutation (subunit A190 S685D) led to higher growth rates in the presence of 6AU or under environmental stress conditions, and was synthetically lethal with a deletion of the Pol I subunit A12.2, suggesting a role in RNA cleavage/elongation or termination. Our results suggest that individual major or constitutively phosphorylated residues contribute to non-essential Pol I-functions.
Mesh Terms:
Amino Acid Sequence, Fungal Proteins, Models, Molecular, Molecular Sequence Data, Mutation, Phenotype, Phosphoproteins, Phosphorylation, Phosphoserine, Phosphothreonine, RNA Polymerase I, Yeasts
Amino Acid Sequence, Fungal Proteins, Models, Molecular, Molecular Sequence Data, Mutation, Phenotype, Phosphoproteins, Phosphorylation, Phosphoserine, Phosphothreonine, RNA Polymerase I, Yeasts
Nucleic Acids Res.
Date: Feb. 01, 2008
PubMed ID: 18084032
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- Interactions 1
- PTM Genes 5