The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform
Elisabeth Gantt - One of the best experts on this subject based on the ideXlab platform.
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interactions of isoprenoid pathway enzymes and indirect stimulation of isoprenoid biosynthesis by Pentose Phosphate Cycle substrates in synechocystis pcc 6803
2012Co-Authors: Kelly Poliquin, Francis X. Cunningham, R. Raymond Gantt, Elisabeth GanttAbstract:Interactions between enzymes of the 2-C-methyl-d-erythritol 4-Phosphate (MEP) pathway of isoprenoid biosynthesis in the cyanobacterium Synechocystis PCC 6803 were examined using a bacterial two-hybrid genetic interaction assay. No protein-protein interactions other than self-interactions were detected, an observation at odds with the concept of a multienzyme complex and metabolic channeling for this pathway. A previously reported stimulation of isoprenoid synthesis by intermediates of the Pentose Phosphate Cycle (PPC) in vitro was not affected by immunodepletion of IDS (LytB), the enzyme that catalyzes the terminal step of the MEP pathway. Addition of various PPC compounds supported a progression of in vitro isoprenoid synthesis, from C5 to C10 to C20, but the PPC compounds did not directly serve as substrates. It is concluded that the in vitro stimulation by PPC compounds is indirect and does not occur via the MEP pathway.
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Inactivation of sll1556 in Synechocystis strain PCC 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro.
Journal of bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Deltasll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Deltasll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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inactivation of sll1556 in synechocystis strain pcc 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro
Journal of Bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Δsll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Δsll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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Isoprenoid Biosynthesis in Synechocystis sp. Strain PCC6803 Is Stimulated by Compounds of the Pentose Phosphate Cycle but Not by Pyruvate or Deoxyxylulose-5-Phosphate
Journal of bacteriology, 2002Co-Authors: Yuri V. Ershov, Francis X. Cunningham, R. Raymond Gantt, Elisabeth GanttAbstract:The photosynthetic cyanobacterium Synechocystis sp. strain PCC6803 possesses homologs of known genes of the non-mevalonate 2-C-methyl-D-erythritol 2-Phosphate (MEP) pathway for synthesis of isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate (DMAPP). Isoprenoid biosynthesis in extracts of this cyanobacterium, measured by incorporation of radiolabeled IPP, was not stimulated by pyruvate, an initial substrate of the MEP pathway in Escherichia coli, or by deoxyxylulose-5-Phosphate, the first pathway intermediate in E. coli. However, high rates of IPP incorporation were obtained with addition of dihydroxyacetone Phosphate (DHAP) and glyceraldehyde 3-Phosphate (GA3P), as well as a variety of Pentose Phosphate Cycle compounds. Fosmidomycin (at 1 micro M and 1 mM), an inhibitor of deoxyxylulose-5-Phosphate reductoisomerase, did not significantly inhibit phototrophic growth of the cyanobacterium, nor did it affect [(14)C]IPP incorporation stimulated by DHAP plus GA3P. To date, it has not been possible to unequivocally demonstrate IPP isomerase activity in this cyanobacterium. The combined results suggest that the MEP pathway, as described for E. coli, is not the primary path by which isoprenoids are synthesized under photosynthetic conditions in Synechocystis sp. strain PCC6803. Our data support alternative routes of entry of Pentose Phosphate Cycle substrates derived from photosynthesis.
Kelly Poliquin - One of the best experts on this subject based on the ideXlab platform.
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interactions of isoprenoid pathway enzymes and indirect stimulation of isoprenoid biosynthesis by Pentose Phosphate Cycle substrates in synechocystis pcc 6803
2012Co-Authors: Kelly Poliquin, Francis X. Cunningham, R. Raymond Gantt, Elisabeth GanttAbstract:Interactions between enzymes of the 2-C-methyl-d-erythritol 4-Phosphate (MEP) pathway of isoprenoid biosynthesis in the cyanobacterium Synechocystis PCC 6803 were examined using a bacterial two-hybrid genetic interaction assay. No protein-protein interactions other than self-interactions were detected, an observation at odds with the concept of a multienzyme complex and metabolic channeling for this pathway. A previously reported stimulation of isoprenoid synthesis by intermediates of the Pentose Phosphate Cycle (PPC) in vitro was not affected by immunodepletion of IDS (LytB), the enzyme that catalyzes the terminal step of the MEP pathway. Addition of various PPC compounds supported a progression of in vitro isoprenoid synthesis, from C5 to C10 to C20, but the PPC compounds did not directly serve as substrates. It is concluded that the in vitro stimulation by PPC compounds is indirect and does not occur via the MEP pathway.
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Inactivation of sll1556 in Synechocystis strain PCC 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro.
Journal of bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Deltasll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Deltasll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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inactivation of sll1556 in synechocystis strain pcc 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro
Journal of Bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Δsll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Δsll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
R. Raymond Gantt - One of the best experts on this subject based on the ideXlab platform.
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interactions of isoprenoid pathway enzymes and indirect stimulation of isoprenoid biosynthesis by Pentose Phosphate Cycle substrates in synechocystis pcc 6803
2012Co-Authors: Kelly Poliquin, Francis X. Cunningham, R. Raymond Gantt, Elisabeth GanttAbstract:Interactions between enzymes of the 2-C-methyl-d-erythritol 4-Phosphate (MEP) pathway of isoprenoid biosynthesis in the cyanobacterium Synechocystis PCC 6803 were examined using a bacterial two-hybrid genetic interaction assay. No protein-protein interactions other than self-interactions were detected, an observation at odds with the concept of a multienzyme complex and metabolic channeling for this pathway. A previously reported stimulation of isoprenoid synthesis by intermediates of the Pentose Phosphate Cycle (PPC) in vitro was not affected by immunodepletion of IDS (LytB), the enzyme that catalyzes the terminal step of the MEP pathway. Addition of various PPC compounds supported a progression of in vitro isoprenoid synthesis, from C5 to C10 to C20, but the PPC compounds did not directly serve as substrates. It is concluded that the in vitro stimulation by PPC compounds is indirect and does not occur via the MEP pathway.
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Inactivation of sll1556 in Synechocystis strain PCC 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro.
Journal of bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Deltasll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Deltasll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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inactivation of sll1556 in synechocystis strain pcc 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro
Journal of Bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Δsll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Δsll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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Isoprenoid Biosynthesis in Synechocystis sp. Strain PCC6803 Is Stimulated by Compounds of the Pentose Phosphate Cycle but Not by Pyruvate or Deoxyxylulose-5-Phosphate
Journal of bacteriology, 2002Co-Authors: Yuri V. Ershov, Francis X. Cunningham, R. Raymond Gantt, Elisabeth GanttAbstract:The photosynthetic cyanobacterium Synechocystis sp. strain PCC6803 possesses homologs of known genes of the non-mevalonate 2-C-methyl-D-erythritol 2-Phosphate (MEP) pathway for synthesis of isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate (DMAPP). Isoprenoid biosynthesis in extracts of this cyanobacterium, measured by incorporation of radiolabeled IPP, was not stimulated by pyruvate, an initial substrate of the MEP pathway in Escherichia coli, or by deoxyxylulose-5-Phosphate, the first pathway intermediate in E. coli. However, high rates of IPP incorporation were obtained with addition of dihydroxyacetone Phosphate (DHAP) and glyceraldehyde 3-Phosphate (GA3P), as well as a variety of Pentose Phosphate Cycle compounds. Fosmidomycin (at 1 micro M and 1 mM), an inhibitor of deoxyxylulose-5-Phosphate reductoisomerase, did not significantly inhibit phototrophic growth of the cyanobacterium, nor did it affect [(14)C]IPP incorporation stimulated by DHAP plus GA3P. To date, it has not been possible to unequivocally demonstrate IPP isomerase activity in this cyanobacterium. The combined results suggest that the MEP pathway, as described for E. coli, is not the primary path by which isoprenoids are synthesized under photosynthetic conditions in Synechocystis sp. strain PCC6803. Our data support alternative routes of entry of Pentose Phosphate Cycle substrates derived from photosynthesis.
Francis X. Cunningham - One of the best experts on this subject based on the ideXlab platform.
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interactions of isoprenoid pathway enzymes and indirect stimulation of isoprenoid biosynthesis by Pentose Phosphate Cycle substrates in synechocystis pcc 6803
2012Co-Authors: Kelly Poliquin, Francis X. Cunningham, R. Raymond Gantt, Elisabeth GanttAbstract:Interactions between enzymes of the 2-C-methyl-d-erythritol 4-Phosphate (MEP) pathway of isoprenoid biosynthesis in the cyanobacterium Synechocystis PCC 6803 were examined using a bacterial two-hybrid genetic interaction assay. No protein-protein interactions other than self-interactions were detected, an observation at odds with the concept of a multienzyme complex and metabolic channeling for this pathway. A previously reported stimulation of isoprenoid synthesis by intermediates of the Pentose Phosphate Cycle (PPC) in vitro was not affected by immunodepletion of IDS (LytB), the enzyme that catalyzes the terminal step of the MEP pathway. Addition of various PPC compounds supported a progression of in vitro isoprenoid synthesis, from C5 to C10 to C20, but the PPC compounds did not directly serve as substrates. It is concluded that the in vitro stimulation by PPC compounds is indirect and does not occur via the MEP pathway.
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Inactivation of sll1556 in Synechocystis strain PCC 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro.
Journal of bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Deltasll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Deltasll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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inactivation of sll1556 in synechocystis strain pcc 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro
Journal of Bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Δsll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Δsll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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Isoprenoid Biosynthesis in Synechocystis sp. Strain PCC6803 Is Stimulated by Compounds of the Pentose Phosphate Cycle but Not by Pyruvate or Deoxyxylulose-5-Phosphate
Journal of bacteriology, 2002Co-Authors: Yuri V. Ershov, Francis X. Cunningham, R. Raymond Gantt, Elisabeth GanttAbstract:The photosynthetic cyanobacterium Synechocystis sp. strain PCC6803 possesses homologs of known genes of the non-mevalonate 2-C-methyl-D-erythritol 2-Phosphate (MEP) pathway for synthesis of isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate (DMAPP). Isoprenoid biosynthesis in extracts of this cyanobacterium, measured by incorporation of radiolabeled IPP, was not stimulated by pyruvate, an initial substrate of the MEP pathway in Escherichia coli, or by deoxyxylulose-5-Phosphate, the first pathway intermediate in E. coli. However, high rates of IPP incorporation were obtained with addition of dihydroxyacetone Phosphate (DHAP) and glyceraldehyde 3-Phosphate (GA3P), as well as a variety of Pentose Phosphate Cycle compounds. Fosmidomycin (at 1 micro M and 1 mM), an inhibitor of deoxyxylulose-5-Phosphate reductoisomerase, did not significantly inhibit phototrophic growth of the cyanobacterium, nor did it affect [(14)C]IPP incorporation stimulated by DHAP plus GA3P. To date, it has not been possible to unequivocally demonstrate IPP isomerase activity in this cyanobacterium. The combined results suggest that the MEP pathway, as described for E. coli, is not the primary path by which isoprenoids are synthesized under photosynthetic conditions in Synechocystis sp. strain PCC6803. Our data support alternative routes of entry of Pentose Phosphate Cycle substrates derived from photosynthesis.
Yuri V. Ershov - One of the best experts on this subject based on the ideXlab platform.
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Inactivation of sll1556 in Synechocystis strain PCC 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro.
Journal of bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Deltasll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Deltasll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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inactivation of sll1556 in synechocystis strain pcc 6803 impairs isoprenoid biosynthesis from Pentose Phosphate Cycle substrates in vitro
Journal of Bacteriology, 2004Co-Authors: Kelly Poliquin, Yuri V. Ershov, Francis X. Cunningham, Tinsay T. Woreta, R. Raymond Gantt, Elisabeth GanttAbstract:In cyanobacteria many compounds, including chlorophylls, carotenoids, and hopanoids, are synthesized from the isoprenoid precursors isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate. Isoprenoid biosynthesis in extracts of the cyanobacterium Synechocystis strain PCC 6803 grown under photosynthetic conditions, stimulated by Pentose Phosphate Cycle substrates, does not appear to require methylerythritol Phosphate pathway intermediates. The sll1556 gene, distantly related to type 2 IPP isomerase genes, was disrupted by insertion of a Kanr cassette. The mutant was fully viable under photosynthetic conditions although impaired in the utilization of Pentose Phosphate Cycle substrates. Compared to the parental strain the Δsll1556 mutant (i) is deficient in isoprenoid biosynthesis in vitro with substrates including glyceraldehyde-3-Phosphate, fructose-6-Phosphate, and glucose-6-Phosphate; (ii) has smaller cells (diameter ca. 13% less); (iii) has fewer thylakoids (ca. 30% less); and (iv) has a more extensive fibrous outer wall layer. Isoprenoid biosynthesis is restored with Pentose Phosphate Cycle substrates plus the recombinant Sll1556 protein in the Δsll1556 supernatant fraction. IPP isomerase activity could not be demonstrated for the purified Sll1556 protein under our in vitro conditions. The reduction of thylakoid area and the effect on outer wall layer components are consistent with an impairment of isoprenoid biosynthesis in the mutant, possibly via hopanoid biosynthesis. Our findings are consistent with an alternate metabolic shunt for biosynthesis of isoprenoids.
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Isoprenoid Biosynthesis in Synechocystis sp. Strain PCC6803 Is Stimulated by Compounds of the Pentose Phosphate Cycle but Not by Pyruvate or Deoxyxylulose-5-Phosphate
Journal of bacteriology, 2002Co-Authors: Yuri V. Ershov, Francis X. Cunningham, R. Raymond Gantt, Elisabeth GanttAbstract:The photosynthetic cyanobacterium Synechocystis sp. strain PCC6803 possesses homologs of known genes of the non-mevalonate 2-C-methyl-D-erythritol 2-Phosphate (MEP) pathway for synthesis of isopentenyl diPhosphate (IPP) and dimethylallyl diPhosphate (DMAPP). Isoprenoid biosynthesis in extracts of this cyanobacterium, measured by incorporation of radiolabeled IPP, was not stimulated by pyruvate, an initial substrate of the MEP pathway in Escherichia coli, or by deoxyxylulose-5-Phosphate, the first pathway intermediate in E. coli. However, high rates of IPP incorporation were obtained with addition of dihydroxyacetone Phosphate (DHAP) and glyceraldehyde 3-Phosphate (GA3P), as well as a variety of Pentose Phosphate Cycle compounds. Fosmidomycin (at 1 micro M and 1 mM), an inhibitor of deoxyxylulose-5-Phosphate reductoisomerase, did not significantly inhibit phototrophic growth of the cyanobacterium, nor did it affect [(14)C]IPP incorporation stimulated by DHAP plus GA3P. To date, it has not been possible to unequivocally demonstrate IPP isomerase activity in this cyanobacterium. The combined results suggest that the MEP pathway, as described for E. coli, is not the primary path by which isoprenoids are synthesized under photosynthetic conditions in Synechocystis sp. strain PCC6803. Our data support alternative routes of entry of Pentose Phosphate Cycle substrates derived from photosynthesis.