Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The levels of transcripts of the cpc operon were highly reduced in a PD-1 mutant of cyanobacterium Synechocystis sp. strain PCC 6714. This was due to a substitution of C for T that occurred at 5 bp upstream of the transcription initiation site of the cpc operon. Any substitution for T at the -5 position drastically reduced both in vivo and in vitro promoter activity in cyanobacterium Synechococcus sp. strain PCC 7942 but not the in vivo activity in Escherichia coli. This suggests that the requirement of -5T appears to be specific for a cyanobacterial RNA polymerase-promoter combination.
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PMID:Thymine at -5 is crucial for cpc promoter activity of Synechocystis sp. strain PCC 6714. 1456 85

Expression profiles of Synechocystis sp. PCC 6803 genes in response to growth in iron-deficient versus iron-sufficient media and after 30 min treatment with H(2)O(2) were determined using a full-genome microarray. We used an anova model that accounted for slide and replicate (random) effects as well as dye (a fixed) effects to identify statistically significant, differentially expressed genes that changed by 1.25-fold or greater during each of these experiments. We utilized this microarray data to identify gene clusters that were regulated under these stresses, because we are interested in cellular redox control and the way in which the cell responds to oxidative stresses. We are particularly interested in using differential expression to help determine the function of genes involved in redox control and cluster analysis aids this process. We concentrated on four gene clusters, two of which were similarly affected by both stresses, and two that were only differentially regulated by one of the stresses. We also analysed the regulatory genes that responded to these oxidative stresses and discussed the changes in transcription of the RNA polymerase sigma factors and the other regulatory proteins, many of which represent two-component regulatory systems.
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PMID:Microarray analysis and redox control of gene expression in the cyanobacterium Synechocystis sp. PCC 6803. 1503 74

We examined the role of SigC (Sll0184), a sigma factor of RNA polymerase (RNAP), in a unicellular cyanobacterium, Synechocystis sp. strain PCC 6803. On the inactivation of sigC, which is an Escherichia coli rpoD homolog, cells were viable but had a low survival rate in the stationary phase of growth under normal physiological conditions, indicating that SigC is a group 2 type sigma factor. In analyses of transcript and protein levels using the sigC knockout strain, it was found that expression of glnB, a nitrogen key regulatory gene, is controlled by SigC in the stationary phase. Primer extension revealed that the glnB nitrogen promoter (P2) was specifically recognized by SigC in the stationary phase under conditions of nitrogen starvation. In vitro studies with purified enzymes indicated effective transcription, on supercoiled DNA templates, from P2 by SigC-RNAP with NtcA which is an activator for nitrogen gene transcription. DNase I footprinting also indicated binding and related sites of NtcA and/or RNAP with SigC on the nitrogen promoter. The unique promoter architecture and the mechanism of transcription by RNAP with SigC are also discussed.
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PMID:SigC, the group 2 sigma factor of RNA polymerase, contributes to the late-stage gene expression and nitrogen promoter recognition in the cyanobacterium Synechocystis sp. strain PCC 6803. 1505 76

The RNA polymerase (RNAP) core enzyme of cyanobacterium Synechocystis sp. strain PCC 6803 was reconstituted with overproduced recombinant subunits and purified with C-terminal histidine-tagged RpoA. The core enzyme with purified a sigma factor, SigA/SigD or SigB, allowed specific in vitro transcription from the light-inducible psbA2 or the dark-/heat-inducible lrtA/hspA promoters, respectively. Further analysis using a mutant psbA2 promoter revealed that the -35 hexamer of the promoter was essential for SigA but not SigD. Similar but distinct patterns of psbA2 transcription were found for two types of RNAP, cyanobacterial (alpha2betabeta'gamma) and E. coli (alpha2betabeta') core enzymes. Specific binding of PCC 6803 RpoC2 (beta') to E. coli core enzyme and its contribution to efficient psbA2 transcription by RNAP-SigA/D suggest that this subunit could confer an important role on the cyanobactrial RNAP. Differences in affinity and specificity among cyanobacterial sigma factors for the core enzyme and promoters were discussed.
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PMID:In vitro transcription analysis by reconstituted cyanobacterial RNA polymerase: roles of group 1 and 2 sigma factors and a core subunit, RpoC2. 1556 50

The sigE gene of Synechocystis sp. PCC 6803 encodes a group 2 sigma factor for RNA polymerase and has been proposed to function in transcriptional regulation of nitrogen metabolism. By using microarray and Northern analyses, we demonstrated that the abundance of transcripts derived from genes important for glycolysis, the oxidative pentose phosphate pathway, and glycogen catabolism is reduced in a sigE mutant of Synechocystis maintained under the normal growth condition. Furthermore, the activities of the two key enzymes of the oxidative pentose phosphate pathway, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, encoded by the zwf and gnd genes were also reduced in the sigE mutant. The dark enhancements in both enzyme activity and transcript abundance apparent in the wild type were eliminated by the mutation. In addition, the sigE mutant showed a reduced rate of glucose uptake and an increased intracellular level of glycogen. Moreover, it was unable to proliferate under the light-activated heterotrophic growth conditions. These results indicate that SigE functions in the transcriptional activation of sugar catabolic pathways in Synechocystis sp. PCC 6803.
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PMID:Positive regulation of sugar catabolic pathways in the cyanobacterium Synechocystis sp. PCC 6803 by the group 2 sigma factor sigE. 1594 48

It has been reported that an RNA polymerase sigma factor, SigC, mainly contributes to specific transcription from the promoter PglnB-54,-53 under nitrogen-deprived conditions during the stationary phase of cell growth in the cyanobacterium Synechocystis sp. strain PCC 6803 (Asayama, M., Imamura, S., Yoshihara, S., Miyazaki, A., Yoshida, N., Sazuka, T., Kaneko, T., Ohara, O., Tabata, S., Osanai, T., Tanaka, K., Takahashi, H., and Shirai, M. (2004) Biosci. Biotechnol. Biochem. 68, 477-487). In this study, we further examined the functions of group 2 sigma factors of RNA polymerase in NtcA-dependent nitrogen-related gene expression in PCC 6803. Results indicated that SigB and SigC contribute to the transcription from PglnB-54,-53 with a sigma factor replaced in a growth phase-dependent manner. We also confirmed the contribution of SigB and SigC to the transcription of other NtcA-dependent genes, glnA, sigE, and amt1, as in the case of glnB. On the other hand, the transcription of glnN was dependent on SigB and SigE. In the SigB and SigC-based regulation, the level of SigB increased, but that of SigC was constant under conditions of nitrogen deprivation. Furthermore, it was found that SigC negatively and positively regulates the level of SigB in the log and stationary phase, respectively. SigC also had a positive effect on the level of sigB transcript during the stationary phase. In contrast, SigB acts positively on SigC levels in both growth phases. These results and previous findings indicated that multiple group 2 sigma factors take part in the control of NtcA-dependent nitrogen-related gene expression in cooperation with a group 1 sigma factor, SigA.
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PMID:Growth phase-dependent activation of nitrogen-related genes by a control network of group 1 and group 2 sigma factors in a cyanobacterium. 1630 55

The widely conserved SUF system is involved in Fe-S cluster repair and biogenesis. In cyanobacterium Synechocystis sp. PCC 6803, transcription of the sufBCDS operon encoding the Suf complex is negatively regulated by the upstream sufR gene encoded by the complementary strand. In this report, two promoters for the sufBCDS operon (P1 and P2) and another promoter for sufR (PsufR) was identified, and it was shown that P1 was activated by a shift to high light conditions. We also showed that Thermosynechococcus SufR negatively regulated P1 and PsufR but not P2, in a reconstituted in vitro transcription system using His(6)-tagged RNA polymerase.
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PMID:Light-responsive transcriptional regulation of the suf promoters involved in cyanobacterium Synechocystis sp. PCC 6803 Fe-S cluster biogenesis. 1694 78

A light-inducible sigma factor of RNA polymerase, SigD, can contributes to the light-induced transcription of psbA in the cyanobacterium Synechocystis sp. PCC 6803. Here, another light-induced sigma factor, SigE, was characterized together with SigD. Results indicated that SigE also contributes to light-induced transcription on the cpcBACD, psbA, petBD and psaAB promoters whose potential sequences are of the Escherichia coli sigma(70)-type. SigD and SigE interfere with each other's expression. A rhythmic expression, in which the periodic peak of SigE exhibits a 24-h interval according to the upcoming night, was observed at the protein level. The cooperation of group 2 sigma factors, SigD and SigE, for light-induced transcription was discussed.
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PMID:Cooperation of group 2 sigma factors, SigD and SigE for light-induced transcription in the cyanobacterium Synechocystis sp. PCC 6803. 1737 15

In photosynthetic organisms, sugar catabolic pathways, such as glycolysis and the oxidative pentose phosphate pathway, are indispensable for survival in the absence of light. In this review, we will focus on the regulation of sugar catabolic gene expression in cyanobacteria, especially that of Synechocystis sp. PCC 6803 (Synechocystis). In Synechocystis, the expression of sugar catabolic genes is activated by the shift from light-to-dark and diurnally during the evening, and positively regulated by a histidine kinase, Hik8, and a RNA polymerase sigma factor, SigE. Mutants for these regulators are defective for survival in the dark and unable to carry out light-activated heterotrophic growth. It has also been shown that transcripts of sugar catabolic genes are increased by nitrogen depletion and a global nitrogen regulator NtcA is essential for the induction. These results indicate a regulatory connection between nitrogen status and sugar catabolism in cyanobacteria.
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PMID:Sugar catabolism regulated by light- and nitrogen-status in the cyanobacterium Synechocystis sp. PCC 6803. 1748

We report on differential gene expression in the cyanobacterium Synechocystis sp. strain PCC 6803 after light-dark transitions in wild-type, DeltasigB, and DeltasigD strains. We also studied the effect of day length in the presence of glucose on a DeltasigB DeltasigE mutant. Our results indicated that the absence of SigB or SigD predominately altered gene expression in the dark or in the light, respectively. In the light, approximately 350 genes displayed transcript levels in the DeltasigD strain that were different from those of the wild type, with over 200 of these up-regulated in the mutant. In the dark, removal of SigB altered more than 150 genes, and the levels of 136 of these were increased in the mutant compared to those in the wild type. The removal of both SigB and SigE had a major impact on gene expression under mixotrophic growth conditions and resulted in the inability of cells to grow in the presence of glucose with 8-h light and 16-h dark cycles. Our results indicated the importance of group II sigma factors in the global regulation of transcription in this organism and are best explained by using the sigma cycle paradigm with the stochastic release model described previously (R. A. Mooney, S. A. Darst, and R. Landick, Mol. Cell 20:335-345, 2005). We combined our results with the total protein levels of the sigma factors in the light and dark as calculated previously (S. Imamura, S. Yoshihara, S. Nakano, N. Shiozaki, A. Yamada, K. Tanaka, H. Takahashi, M. Asayama, and M. Shirai, J. Mol. Biol. 325:857-872, 2003; S. Imamura, M. Asayama, H. Takahashi, K. Tanaka, H. Takahashi, and M. Shirai, FEBS Lett. 554:357-362, 2003). Thus, we concluded that the control of global transcription is based on the amount of the various sigma factors present and able to bind RNA polymerase.
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PMID:Role of sigma factors in controlling global gene expression in light/dark transitions in the cyanobacterium Synechocystis sp. strain PCC 6803. 1772 Jul 83


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