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 main virulence factors of the phytopathogenic bacteria Erwinia chrysanthemi are pectinases that cleave pectin, a major constituent of the plant cell wall. The cyclic AMP receptor protein (CRP) was identified as the main activator of the pectinolysis genes. Gel shift and DNase I footprinting experiments showed that the purified E. chrysanthemi CRP protein binds specifically to the promoter regions of seven pectinolysis genes (pelB, pelC, pelD, pelE, ogl, kduI and kdgT) whose expression is positively regulated in vivo by CRP. In contrast, no interaction was observed between CRP and the promoter-operator region of pelA, whose expression is negatively regulated in vivo by CRP. Primer extension experiments demonstrated that each of the pelB, pelC, pelE and kduI genes is expressed from a unique sigma70 promoter, whereas ogl and kdgT possess three and two functional promoters respectively. The position of the CRP binding site relative to the transcription start site suggests that CRP acts as a primary activator at the pelB (via the CRP binding site 1), pelC, pelE, pelD, kdgTP1 and oglP2 promoters. In contrast, transcription at the kduI, oglP1 promoters seems to require another transcriptional activator in synergy with CRP. Investigation of the simultaneous binding of CRP and KdgR, the main repressor of pectinolysis genes, to the regulatory regions of pelB, pelC, pelD, pelE, ogl, kduI and kdgT genes showed that binding of KdgR is preferential and exclusive in the case of ogl and kdgT, whereas the binding of these two regulators is independent in the case of pelB, pelC, pelD, pelE and kduI. Taken together, our data suggest that the antagonistic effects of CRP and KdgR on the expression of the pectinolysis genes occur by different mechanisms, including direct competition between the two regulators or between the repressor and RNA polymerase for the occupation of a common DNA region on the target genes.
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PMID:Antagonistic effect of CRP and KdgR in the transcription control of the Erwinia chrysanthemi pectinolysis genes. 942 43

In Corynebacterium glutamicum the promoter of the araBAD Escherichia coli gene is positively regulated by both arabinose and the araC gene product, as it is the case in the natural host. If the L-arabinose inducer and an active araC gene are present, significant amounts of araBAD promoter expression take place in the absence of the E. coli CRP protein. These results show that the C. glutamicum RNA polymerase is activated by the E. coli positive regulator of transcription AraC.
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PMID:Positively regulated expression of the Escherichia coli araBAD promoter in Corynebacterium glutamicum. 1023 30

The in vitro formation of transcription complexes with Escherichia coli RNA polymerase was monitored using fluorescence anisotropy measurements of labeled fragments of DNA. The multicomponent system consisted of holo or core RNA polymerase (RNAP) and lac or gal promoter fragments of DNA (in different configurations), in the presence or absence of CRP activator protein (wt or mutants) with its ligand, cAMP. Values of the apparent binding constants characterizing the system were obtained, as a result of all processes taking place in the system. The interaction of the promoters with core RNAP in the absence of CRP protein was characterized by apparent binding constants of 0.67 and 1.9 x 10(6) M(-1) for lac166 and gal178, respectively, and could be regarded as nonspecific. The presence of wt CRP enhanced the strength of the interaction of core RNAP with the promoter, and even in the case of gal promoter it made this interaction specific (apparent binding constant 2.93 x 10(7) M(-1)). Holo RNAP bound the promoters significantly more strongly than core RNAP did (apparent binding constants 1.46 and 40.14 x 10(6) M(-1) for lac166 and gal178, respectively), and the presence of CRP also enhanced the strength of these interactions. The mutation in activator region 1 of CRP did not cause any significant disturbances in the holo RNAP-lac promoter interaction, but mutation in activator region 2 of the activator protein substantially weakened the RNAP-gal promoter interaction.
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PMID:Quantitative analysis of the ternary complex of RNA polymerase, cyclic AMP receptor protein and DNA by fluorescence anisotropy measurements. 1878 13

Gene vfr previously described only in Pseudomonas aeruginosa was cloned, identified, and sequenced in cells of Pseudomonas chlororaphis 449; its localization in the chromosome was determined. Amino acid sequence of the protein encoded by gene vfr in P. chlororaphis 449 was shown to have a 83% identity with the Vfr protein of P. aeruginosa PAO1 and a 63% identity with the CRP protein of Escherichia coli. Amino acid residues that ensure the most important structural properties of the CRP protein, i.e., its binding to cAMP, RNA polymerase, and DNA, were identical or highly conserved in Vfr proteins of P. aeruginosa and P. chlororaphis 449. The cloned vfr gene of P. chlororaphis 449 was partially complementary to mutation at crp gene in cells of E. coli AM306 enhancing ten times synthesis of CRP protein-dependent beta-galactosidase. Unlike P. aeruginosa, the Vfr protein in cells of P. chlororaphis 449 does not participate in the regulation of synthesis of N-acyl-homoserine lactones.
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PMID:[Structure and expression of gene vfr in Pseudomonas chlororaphis 449]. 1982 40