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)

The two highly homologous cbb operons of the facultative chemoautotroph Ralstonia eutropha H16 encode most enzymes of the Calvin-Benson-Bassham carbon reduction cycle. Their transcriptional regulation was investigated both in vitro and in vivo to identify a metabolic signal involved in this process. For this purpose an in vitro transcription system employing the DNA-dependent RNA polymerase purified from R. eutropha was established. The enzyme from Escherichia coli was also used in verifying comparative studies. Plasmid DNA carrying the control region of the chromosomal cbb operon served as template. In the homologous as well as the heterologous system specific transcripts synthesized under the control of the operon promoter PcbbL were observed, depending on the structure of the tested promoter variant as well as the presence or absence of the activator protein CbbR. Unlike mutationally improved PcbbL variants, the wild-type promoter remained inactive, even in the presence of CbbR together with various potential signal metabolites. CbbR stimulated PcbbL mutants with intermediate basal activity. Phosphoenolpyruvate (PEP) was identified as a negative effector of CbbR that inhibited PcbbL-directed transcription and increased the operator-binding affinity of the protein. This CbbR-mediated inhibition was confirmed by assaying wild-type PcbbL operon fusions in glucose- or succinate-grown cells of E. coli, which contain greatly different concentrations of PEP. It is concluded that at least one additional protein must participate in the overall control of the cbb operons in R. eutropha.
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PMID:Phosphoenolpyruvate is a signal metabolite in transcriptional control of the cbb CO2 fixation operons in Ralstonia eutropha. 1093 40

Photorespiration is essential for the detoxification of glycolate and recycling of carbon to the Calvin Benson Bassham cycle. Enzymes participating in the pathway have been identified, and investigations now focus on the regulation of photorespiration by transporters and metabolites. However, regulation of photorespiration on the gene level has not been intensively studied. Here, we show that maximum transcript abundance of Glu:glyoxylate aminotransferase 1 (GGT1) is regulated by intron-mediated enhancement (IME) of the 5' leader intron rather than by regulatory elements in the 5' upstream region. The intron is rich in CT-stretches and contains the motif TGTGATTTG that is highly similar to the IME-related motif TTNGATYTG. The GGT1 intron also confers leaf-specific expression of foreign promoters. Quantitative PCR analysis and GUS activity measurements revealed that IME of the GGT1 5'UTR intron is controlled on the transcriptional level. IME by the GGT1 5'UTR intron was at least 2-fold. Chromatin immunoprecipitation experiments showed that the abundance of RNA polymerase II binding to the intron-less construct is reduced.
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PMID:The 5'UTR Intron of Arabidopsis GGT1 Aminotransferase Enhances Promoter Activity by Recruiting RNA Polymerase II. 2741 88