Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report the characterization of a mutation affecting tau 138, the largest subunit of yeast transcription factor IIIC (TFIIIC). A previously described thermosensitive mutation (tsv115), tightly linked to the centromere of chromosome I (Harris, S.D., and Pringle, J.R. (1991) Genetics 127, 279-285) is shown to lie in the TFC3 gene which encodes tau 138. The tau 138 subunit carrying this mutation bears a single substitution of Glu for Gly at position 349 (G349E). In extracts from mutant cells, both the level of TFIIIC and its affinity for tDNA were found to be reduced. The tDNA binding activity of mutant TFIIIC protein was very sensitive to mild heat treatments, and TFIIIC-DNA interaction was inhibited at moderate salt concentrations, as evidenced by gel shift assays. In addition, the tsv115 mutation affected 5 S RNA synthesis in vitro, suggesting that the tau 138 subunit also plays a role in recognition of the TFIIIA-5 S DNA complex. Multicopy suppressors of the TFIIIC defect were sought to reveal components participating in TFIIIC function. One class of suppressors encodes known components of the transcription machinery: two TFIIIC subunits, tau 95 and tau 131, the 70-kDa subunit of TFIIIB, TBP, and a shared subunit of RNA polymerase (pol) I, II, and III, ABC10 alpha; it also includes genes potentially related to pol III function, such as SRP40 which also suppresses a mutation in a subunit shared by RNA polymerases I and III. A second class of suppressors is not involved in transcription but alleviates the main physiological defects of mutant cells. It includes RPR1 and NOP1, required for the maturation of pre-tRNA and pre-rRNA, respectively.
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PMID:A mutation in the largest subunit of yeast TFIIIC affects tRNA and 5 S RNA synthesis. Identification of two classes of suppressors. 808 43

Trypanosomatids possess two homologues of Nopp140: a canonical Nopp140 and a Nopp140-like protein (TbNoLP) in which a GAR domain replaces the C-terminal SRP40 domain. Both are phosphorylated and coimmunoprecipitate with RNA polymerase I. Each paralogue has a distinct subnuclear localization, and depletion of TbNoLP produces an enlarged nucleolus in which TbNopp140-containing regions disperse. The restricted occurrence pattern of NoLP proteins reflects an intriguing convergence in evolution, suggestive of a function in nucleoplasmic small nucleolar ribonucleoprotein shuttling.
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PMID:Characterization and differential nuclear localization of Nopp140 and a novel Nopp140-like protein in trypanosomes. 1668 65