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)

In the present work, the RNA polymerase activity of the human mitochondrial RNA polymerase mature protein (h-mtRPOLm) is shown, and its molecular activity calculated (2.1+/-0.9 min(-1)). An activity analysis of h-mtRPOLm and deleted versions of it has demonstrated that the entire recombinant protein is required for this activity. In addition, h-mtRPOLm alone or in presence of the known mitochondrial transcription factors (human mitochondrial transcription factor A and/or human mitochondrial transcription termination factor) is not able to initiate transcription from the specific human mitochondrial promoters pointing to the existence of a human mitochondrial transcription factor B-like protein.
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PMID:A study on the human mitochondrial RNA polymerase activity points to existence of a transcription factor B-like protein. 1151 53

Despite the crucial importance of mitochondrial transcription, knowledge of its regulation is poor. Therefore, characterization of mammalian mitochondrial transcription termination factor (mTERF) functionality and regulation is of fundamental biological interest in order to understand the regulation of mitochondrial transcription. Here we report that mTERF is the first protein having a role in mammalian mitochondrial gene expression that appears to be controlled by phosphorylation. Recombinant mature rat mTERF protein has specific DNA-binding capacity for the sequence required for transcription termination. Furthermore, unlike recombinant human mTERF, the rat protein bound to its mitochondrial DNA binding site promotes the termination of transcription initiated with heterologous RNA polymerase. Interestingly, mTERF is a phosphoprotein with four phosphate groups, and while the DNA-binding activity of mTERF is unaffected by the phosphorylation/dephosphorylation state, only the phosphorylated form of the protein is active for termination activity. Moreover, natural human mTERF is also a phosphoprotein and its termination activity is inhibited by dephosphorylation. These data suggest that mTERF functioning in vivo is regulated by phosphorylation.
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PMID:Phosphorylation of rat mitochondrial transcription termination factor (mTERF) is required for transcription termination but not for binding to DNA. 1508 85

Most chloroplast and mitochondrial proteins are encoded by nuclear genes, whose functions remain largely unknown because mutant alleles are lacking. A reverse genetics screen for mutations affecting the mitochondrial transcription termination factor (mTERF) family in Arabidopsis thaliana allowed us to identify 75 lines carrying T-DNA insertions. Two of them were homozygous for insertions in the At4g14605 gene, which we dubbed MDA1 (MTERF DEFECTIVE IN Arabidopsis1). The mda1 mutants exhibited altered chloroplast morphology and plant growth, and reduced pigmentation of cotyledons, leaves, stems and sepals. The mda1 mutations enhanced salt and osmotic stress tolerance and altered sugar responses during seedling establishment, possibly as a result of reduced ABA sensitivity. Loss of MDA1 function caused up-regulation of the RpoTp/SCA3 nuclear gene encoding a plastid RNA polymerase and modified the steady-state levels of chloroplast gene transcripts. Double mutant analyses indicated that MDA1 and the previously described mTERF genes SOLDAT10 and RUG2 act in different pathways. Our findings reveal a new role for mTERF proteins in the response to abiotic stress, probably through perturbed ABA retrograde signalling resulting from a disruption in chloroplast homeostasis.
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PMID:Arabidopsis MDA1, a nuclear-encoded protein, functions in chloroplast development and abiotic stress responses. 2290 86

To enhance our understanding of the roles of mitochondrial transcription termination factors (mTERFs) in plants, we have taken a reverse genetic approach in Arabidopsis thaliana. One of the mutants isolated carried a novel allele of the mTERF6 gene, which we named mterf6-5. mTERF6 is a chloroplast and mitochondrial localised protein required for the maturation of chloroplast isoleucine tRNA. The mterf6-5 plants are pale and exhibit markedly reduced growth, and altered leaf and chloroplast development. Our qRT-PCR analyses revealed mis-expression of several plastid, mitochondrial and nuclear genes in mterf6-5 plants. Synergistic phenotypes were observed in double mutant combinations of mterf6-5 with alleles of other mTERF genes as well as with scabra3-2, affected in the plastid RpoTp RNA polymerase; these observations suggest a functional relationship between mTERF6, other mTERFs and SCA3. The mterf6-5 mutation also enhanced the leaf dorsoventral polarity defects of the asymmetric leaves1-1 (as1-1) mutant, which resulted in radial leaves. This interaction seemed specific of the impaired mTERF6 function because mutations in the mTERF genes MDA1 or TWR-1/mTERF9 did not result in radialised leaves. Furthermore, the mterf6-5 mutation dramatically increased the leaf phenotype of as2-1 and caused lethality early in vegetative development. Our results uncover a new role for mTERF6 in leaf patterning and highlight the importance of mTERFs in plant development.
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PMID:Arabidopsis mTERF6 is required for leaf patterning. 2924 61