Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0031511 (pheochromocytoma)
 14,622 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Disruption of the ccmM gene in the cyanobacterium Synechocystis sp. PCC 6803 causes a deficiency of carboxysomes and impairs growth in ambient CO2. The effect of this gene defect on cellular metabolism was investigated using electron microscopy, biochemical and fluorescence analysis. Mutant cells were devoid of the characteristic dense polyhedral bodies called carboxysomes. The photosynthetic oxygen evolution was considerably lower in mutant cells compared to wild type, while Rubisco activity in cell extracts was similar. During photosynthetic CO2-dependent oxygen evolution, Rubisco Vmax dropped from 142 micromol mg-1 chlorophyll h-1 (WT) to 77 micromol mg-1 chlorophyll h-1 in the mutant cells, and the Km for Ci (inorganic carbon) increased from 0.5 mM (WT) to 40 mM. The fluorescent indicator, acridine yellow, was used for non-invasive measurements of cytoplasmic pH changes in whole cells induced by addition of Ci, making use of the decrease in fluorescence yield that accompanies cytoplasmic acidification. The experimental results indicate that control of the cytoplasmic pH is linked to the internal carbon pool (Ci). Both wild-type and ccmM-deficient cells showed a linear response of acridine yellow fluorescence quenching and, thus, of internal acidification, with respect to externally added inorganic carbon. However, the fluorescence analysis of mutant (carboxysome-free) cells indicated slower kinetics of Ci accumulation.
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PMID:Monitoring cytosolic pH of carboxysome-deficient cells of Synechocystis sp. PCC 6803 using fluorescence analysis. 1602 6

Precipitation of CaCO3 catalyzed by the growth and physiology of cyanobacteria in the genus Synechococcus represents a potential mechanism for sequestration of atmospheric CO2 produced during the burning of coal for power generation. Synechococcus sp. strain PCC 8806 and Synechococcus sp. strain PCC 8807 were tested in microcosm experiments for their ability to calcify when exposed to a fixed calcium concentration of 3.4 mM and dissolved inorganic carbon concentrations of 0.5, 1.25 and 2.5 mM. Synechococcus sp. strain PCC 8806 removed calcium continuously over the duration of the experiment producing approximately 18.6 mg of solid phase calcium. Calcium removal occurred over a two-day time period when Synechococcus sp. strain PCC 8807 was tested and only 8.9 mg of solid phase calcium was produced. Creation of an alkaline growth environment catalyzed by the physiology of the cyanobacteria appeared to be the primary factor responsible for CaCO3 precipitation in these experiments.
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PMID:Calcium carbonate formation by Synechococcus sp. strain PCC 8806 and Synechococcus sp. strain PCC 8807. 1628 26

The Slr1991 adenylyl cyclase of the model prokaroyte Synechocystis PCC 6803 was stimulated 2-fold at 20 mM total C(i) (inorganic carbon) at pH 7.5 through an increase in k(cat). A dose response demonstrated an EC50 of 52.7 mM total C(i) at pH 6.5. Slr1991 adenylyl cyclase was activated by CO2, but not by HCO3-. CO2 regulation of adenylyl cyclase was conserved in the CyaB1 adenylyl cyclase of Anabaena PCC 7120. These adenylyl cyclases represent the only identified signalling enzymes directly activated by CO2. The findings prompt an urgent reassessment of the activating carbon species for proposed HCO3--activated adenylyl cyclases.
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PMID:Regulation of prokaryotic adenylyl cyclases by CO2. 1670 64

Glycogen phosphorylase (GlgP, EC 2.4.1.1) catalyzes the cleavage of glycogen into glucose-1-phosphate (Glc-1-P), the first step in glycogen catabolism. Two glgP homologues are found in the genome of Synechocystis sp. PCC 6803, a unicellular cyanobacterium: sll1356 and slr1367. We report on the different functions of these glgP homologues. sll1356, rather than slr1367, is essential for growth at high temperatures. On the other hand, when CO2-fixation and the supply of glucose are both limited, slr1367 is the key factor in glycogen metabolism. In cells growing autotrophically, sll1356 plays a more important role in glycogen digestion than slr1367. This functional divergence is also supported by a phylogenetic analysis of glgP homologues in cyanobacteria.
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PMID:The functional divergence of two glgP homologues in Synechocystis sp. PCC 6803. 1684 45

Cyanobacteria, blue-green algae, are the most abundant autotrophs in aquatic environments and form the base of the food chain by fixing carbon and nitrogen into cellular biomass. To compensate for the low selectivity of Rubisco for CO2 over O2, cyanobacteria have developed highly efficient CO2-concentrating machinery of which the ABC transport system CmpABCD from Synechocystis PCC 6803 is one component. Here, we have described the structure of the bicarbonate-binding protein CmpA in the absence and presence of bicarbonate and carbonic acid. CmpA is highly homologous to the nitrate transport protein NrtA. CmpA binds carbonic acid at the entrance to the ligand-binding pocket, whereas bicarbonate binds in nearly an identical location compared with nitrate binding to NrtA. Unexpectedly, bicarbonate binding is accompanied by a metal ion, identified as Ca2+ via inductively coupled plasma optical emission spectrometry. The binding of bicarbonate and metal appears to be highly cooperative and suggests that CmpA may co-transport bicarbonate and calcium or that calcium acts a cofactor in bicarbonate transport.
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PMID:The structure of a cyanobacterial bicarbonate transport protein, CmpA. 1712 16

Iron induced changes in growth, N2-fixation, CO2 fixation and photosynthetic activity were studied in a diazotrophic cyanobacterium Anabaena PCC 7120. Iron at 50 microM concentration supported the maximum growth, heterocyst frequency, CO2 fixation, photosystem I (PS I), photosystem II (PS II) and nitrogenase activities in the organism. Higher concentration of iron inhibited these processes. Chl a and PS II activities were more sensitive to iron than the protein and PS I activity.
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PMID:Iron induced metabolic changes in the diazotrophic cyanobacterium Anabaena PCC 7120. 1713 17

Transgenic Arabidopsis thaliana and Nicotiana tabacum plants that express ictB, a gene involved in HCO3- accumulation within the cyanobacterium Synechococcus sp. PCC 7942, exhibited significantly faster photosynthetic rates than the wild-types under limiting but not under saturating CO2 concentrations. Under conditions of low relative humidity, growth of the transgenic A. thaliana plants was considerably faster than the wild-type. This enhancement of growth was not observed under humid conditions. There was no difference in the amount of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) detected in the wild-types and their respective transgenic plants. Following activation in vitro, the activities of RubisCO from either low- or high-humidity-grown transgenic plants were similar to those observed in the wild-types. In contrast, the in vivo RubisCO activity, i.e. without prior activation, in plants grown under low humidity was considerably higher in ictB-expressing plants than in their wild-types. The CO2 compensation point in the transgenic plants that express ictB was lower than in the wild-types, suggesting that the concentration of CO2 in close proximity to RubisCO was higher. This may explain the higher activation level of RubisCO and enhanced photosynthetic activities and growth in the transgenic plants. These data indicated a potential use of ictB for the stimulation of crop yield.
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PMID:Enhanced photosynthesis and growth of transgenic plants that express ictB, a gene involved in HCO3- accumulation in cyanobacteria. 1714 79

The hybrid sensory histidine kinase Slr1759 of the cyanobacterium Synechocystis sp. strain PCC 6803 contains multiple sensory domains and a multi-step phosphorelay system. Immuno blot analysis provided evidence that the histidine kinase Slr1759 is associated with the cytoplasmic membrane. The gene slr1759 is part of an operon together with slr1760, encoding a response regulator. A comparative investigation was performed on Synechocystis sp. strain PCC 6803 wild type (WT) and an insertionally inactivated slr1759-mutant (Hik14) which also lacks the transcript for the response regulator Slr1760. The mutant Hik14 grew significantly slower than WT in the early growth phase, when both were inoculated with a low cell density into BG11 medium without additional buffer and when aerated with air enriched with 2% CO2. Since the aeration with CO2-enriched air results in a decrease of the pH value in the medium, the growth experiments indicated that Hik14 is not able to adjust its metabolic activities as rapidly as WT to compensate for a larger decrease of the pH value in the medium. No significant differences in growth between Hikl4 and WT were observed when cells were inoculated with a higher cell density in BG11 medium or when the BG11 medium contained 50 mM Epps-NaOH, pH 7.5, to prevent the pH drop. This Hik14 phenotype has so far only been seen under the above defined growth condition. Results of photosynthetic activity measurements as well as Northern blot-, immuno blot-, and metabolite analyses suggest that the two-component system Slr1759/Slr1760 has a function in the coordination of several metabolic activities which is in good agreement with the complex domain structure of Slr1759. The direct targets of this two-component system have so far not been identified.
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PMID:Physiological and molecular characterization of a Synechocystis sp. PCC 6803 mutant lacking histidine kinase Slr1759 and response regulator Slr1760. 1729 99

Global transcriptional responses to dehydration and rehydration were determined in Anabaena sp. PCC 7120. Nearly 300 genes were up- or downregulated during both dehydration and rehydration. While as many as 133 genes showed dehydration-specific downregulation, only 29 genes showed dehydration-specific upregulation. In contrast, while only 13 genes showed rehydration-specific downregulation, as many as 259 genes showed rehydration-specific upregulation. The genes upregulated during rehydration responded rapidly and transiently, whereas those upregulated during dehydration did so gradually and persistently. The expression of various genes involved in DNA repair, protein folding and NAD synthesis, as well as genes responding to nitrogen depletion and CO2 limitation, was upregulated during rehydration. Although no genes for transcriptional regulators showed dehydration-specific upregulation, eight showed rehydration-specific upregulation. Among them, two genes, ancrpB and alr0618, encode putative transcriptional activators of the cAMP receptor protein (CRP) family. DNA microarray analysis using gene disruptants revealed that AnCrpB and Alr0618 regulate the genes induced by nitrogen depletion and by CO2 limitation, respectively. We conclude that rehydration is a complex process in which the expression of certain genes, particularly those for metabolism, is dramatically induced.
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PMID:Dynamic transcriptional changes in response to rehydration in Anabaena sp. PCC 7120. 1797 76

The cmp operon of the cyanobacterium Synechococcus elongatus strain PCC 7942, encoding the subunits of the ABC-type bicarbonate transporter, is activated under CO2-limited growth conditions in a manner dependent on CmpR, a LysR family transcription factor of CbbR subfamily. The 0.7 kb long regulatory region of the operon carried a single promoter, which responded to CO2 limitation. Using the luxAB reporter system, three cis-acting elements involved in the low-CO2 activation of transcription, each consisting of a pair of LysR recognition signatures overlapping at their ends, were identified in the regulatory region. CmpR was shown to bind to the regulatory region, yielding several DNA-protein complexes in gel shift assays. Addition of ribulose-1,5-bisphosphate (> 1 mM) or 2-phosphoglycolate (> 10 microM) enhanced the binding of CmpR in a concentration-dependent manner, promoting formation of large DNA-protein complexes. Given the involvement of O2 in adaptive responses of cyanobacteria to low-CO2 conditions, our results suggest that 2-phosphoglycolate, which is produced by oxygenation by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) of ribulose-1,5-bisphosphate under CO2-limited conditions, acts as the co-inducer in the activation of the cmp operon by CmpR.
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PMID:Mechanism of low CO2-induced activation of the cmp bicarbonate transporter operon by a LysR family protein in the cyanobacterium Synechococcus elongatus strain PCC 7942. 1831 74


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