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

A putative ATPase gene was cloned from Trypanosoma brucei genomic DNA. The length of the gene open reading frame is 3,033 bp, predicting a protein of about 110 kDa. The sequence of this protein shares 10 blocks of homology with other eukaryotic ATPases, including the putative phosphorylation site characteristic of P-ATPases. Its hydropathy profile reveals 8-10 potential membrane-spanning regions. While the amino acid sequence of the T. brucei ATPase shows only 25% overall homology with its counterpart from the related kinetoplastid protozoan Leishmania donovani, 49% sequence conservation is found when compared with the calcium-ATPase from rabbit sarcoplasmic reticulum. This gene is present in only one copy, localized in the large chromosome fraction. It is transcribed at a similar level in procyclic and bloodstream forms, as a 4.3-kb mRNA. Run-on assays suggest continuous transcription of the gene and flanking sequences over at least 10 kb, by a RNA polymerase sensitive to alpha-amanitin. Transcription inhibition by UV irradiation suggests that the ATPase gene is more than 4 kb downstream from its promoter.
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PMID:Structure and transcription of a P-ATPase gene from Trypanosoma brucei. 183 43

We have determined the nucleotide sequences of three mutant rho genes encoding hyperfunctional rho proteins (rho S) together with their parent allele, rho-ts702. These mutant rho factors contain the following amino acid changes as deduced from their sequences: (1) the thermo-labile mutant, rho-ts702, has Thr304 substituting for Ala; (2) rho S-77 and rho S-81, which are selectively altered in the primary polynucleotide binding site, share an identical mutation, Leu3----Phe; (3) rho S-82, which is altered in both the primary and secondary polynucleotide binding sites, carries three amino acid substitutions together, Leu3----Phe, Asp156----Asn and Thr323----Ile. Dissection and functional characterization of each mutation in rho S-82 have revealed that Ile323 alone is responsible for alterations in both the secondary RNA interaction and the terminator selectivity observed with the original mutant, rho S-82. Taken together, these results not only confirm our proposal in the accompanying paper that the primary and secondary RNA binding sites differently contribute in determining the overall efficiency and site-specificity of termination, respectively, but also support the possibility that these binding sites exist as structurally distinct domains in rho protein. In contrast, Asn156 was shown to cause decreased termination efficiency, though it had no influence on RNA interactions. Thus, this amino acid residue appears to be associated with still another rate-determining step of termination, for instance, interactions between rho and RNA polymerase. On the basis of Chou-Fasman secondary structure predictions as well as amino acid sequence comparison with F1-ATPase, we discuss how the proposed domains are structurally and functionally related to the putative ATPase reactive center of rho protein.
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PMID:Mutant rho factors with increased transcription termination activities. II. Identification and functional dissection of amino acid changes. 247 57

Vaccinia virus early transcription factor (VETF) activates the transcription of early gene templates by the viral RNA polymerase. VETF is a heterodimeric protein that binds to transcription promoters and has an associated DNA-dependent ATPase activity. The small subunit of VETF has sequences resembling two motifs commonly found in ATPases: an A-type ATP binding motif and a DEAH box. To investigate the functional role of the ATPase activity, we have analyzed the effect of mutations in each of the putative ATPase motifs. Recombinant VETF was expressed in HeLa cells using a vaccinia virus/T7 RNA polymerase system. Simultaneous expression of both subunits of VETF was required to obtain soluble protein with promoter binding, DNA-dependent ATPase, and transcription activation functions. The mutants with altered ATPase motifs retained promoter binding activity but had no detectable ATPase activity and no ability to activate transcription. The DEAH box mutant was shown to dominantly repress transcription activation by wildtype VETF. These results indicate that the DNA-dependent ATPase activity of VETF is essential for its transcription activation function.
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PMID:The DNA-dependent ATPase activity of vaccinia virus early gene transcription factor is essential for its transcription activation function. 837 62

The SUG1 gene of Saccharomyces cerevisiae encodes a putative ATPase. Mutations in SUG1 were isolated as suppressors of a mutation in the transcriptional activation domain of GAL4. Sug1 was recently proposed to be a subunit of the RNA polymerase II holoenzyme and to mediate the association of transcriptional activators with holoenzyme. We show here that Sug1 is not a subunit of the holoenzyme, at least in its purified form, but of the 26S proteasome, a large complex of relative molecular-mass 2,000K that catalyses the ATP-dependent degradation of ubiquitin-protein conjugates. Sug1 co-purifies with the proteasome in both conventional and nickel-chelate affinity chromatography. Our observations account for the reduced ubiquitin-dependent proteolysis in sug1 mutants and suggest that the effects of sug1 mutations on transcription are indirect results of defective proteolysis.
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PMID:Identification of the gal4 suppressor Sug1 as a subunit of the yeast 26S proteasome. 862 1