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Xiao-song Gong - One of the best experts on this subject based on the ideXlab platform.
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electron transfer and stability of the cytochrome b6f complex in a small domain Deletion Mutant of cytochrome f
Journal of Biological Chemistry, 2001Co-Authors: Xiao-song Gong, Susana Chung, Javier G FernandezvelascoAbstract:The lumen segment of cytochrome f consists of a small and a large domain. The role of the small domain in the biogenesis and stability of the cytochrome b(6)f complex and electron transfer through the cytochrome b(6)f complex was studied with a small domain Deletion Mutant in Chlamydomonas reinhardtii. The Mutant is able to grow photoautotrophically but with a slower rate than the wild type strain. The heme group is covalently attached to the polypeptide, and the visible absorption spectrum of the Mutant protein is identical to that of the native protein. The kinetics of electron transfer in the Mutant were measured by flash kinetic spectroscopy. Our results show that the rate for the oxidation of cytochrome f was unchanged (t(12) = approximately 100 micros), but the half-time for the reduction of cytochrome f is increased (t(12) = 32 ms; for wild type, t(12) = 2.1 ms). Cytochrome b(6) reduction was slower than that of the wild type by a factor of approximately 2 (t(12) = 8.6 ms; for wild type, t(12) = 4.7 ms); the slow phase of the electrochromic band shift also displayed a slower kinetics (t(12) = 5.5 ms; for wild type, t(12) = 2.7 ms). The stability of the cytochrome b(6)f complex in the Mutant was examined by following the kinetics of the degradation of the individual subunits after inhibiting protein synthesis in the chloroplast. The results indicate that the cytochrome b(6)f complex in the small domain Deletion Mutant is less stable than in the wild type. We conclude that the small domain is not essential for the biogenesis of cytochrome f and the cytochrome b(6)f complex. However, it does have a role in electron transfer through the cytochrome b(6)f complex and contributes to the stability of the complex.
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Electron transfer and stability of the cytochrome b6f complex in a small domain Deletion Mutant of cytochrome f.
Journal of Biological Chemistry, 2001Co-Authors: Xiao-song Gong, Susana Chung, Javier G. Fernández-velascoAbstract:Abstract The lumen segment of cytochrome fconsists of a small and a large domain. The role of the small domain in the biogenesis and stability of the cytochromeb 6 f complex and electron transfer through the cytochrome b 6 f complex was studied with a small domain Deletion Mutant in Chlamydomonas reinhardtii. The Mutant is able to grow photoautotrophically but with a slower rate than the wild type strain. The heme group is covalently attached to the polypeptide, and the visible absorption spectrum of the Mutant protein is identical to that of the native protein. The kinetics of electron transfer in the Mutant were measured by flash kinetic spectroscopy. Our results show that the rate for the oxidation of cytochrome f was unchanged (t = ∼100 μs), but the half-time for the reduction of cytochrome f is increased (t = 32 ms; for wild type,t = 2.1 ms). Cytochromeb 6 reduction was slower than that of the wild type by a factor of approximately 2 (t = 8.6 ms; for wild type, t = 4.7 ms); the slow phase of the electrochromic band shift also displayed a slower kinetics (t = 5.5 ms; for wild type,t = 2.7 ms). The stability of the cytochromeb 6 f complex in the Mutant was examined by following the kinetics of the degradation of the individual subunits after inhibiting protein synthesis in the chloroplast. The results indicate that the cytochromeb 6 f complex in the small domain Deletion Mutant is less stable than in the wild type. We conclude that the small domain is not essential for the biogenesis of cytochromef and the cytochromeb 6 f complex. However, it does have a role in electron transfer through the cytochromeb 6 f complex and contributes to the stability of the complex.
Koji Ichinose - One of the best experts on this subject based on the ideXlab platform.
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identification of the actinorhodin monomer and its related compound from a Deletion Mutant of the actva orf4 gene of streptomyces coelicolor a3 2
Bioorganic & Medicinal Chemistry Letters, 2012Co-Authors: Takaaki Taguchi, Susumu Okamoto, Takayuki Ebihara, Atsushi Furukawa, Yumiko Hidaka, Ryuji Ariga, Koji IchinoseAbstract:An oxygenated derivative of dihydrokalafungin (DHK) was isolated from a Deletion Mutant of the actVA-ORF4 gene involved in the biosynthesis of a dimeric benzoisochromanequinone (BIQ) antibiotic, actinorhodin (ACT), in Streptomyces coelicolor A3(2). Spectroscopic analysis elucidated its structure as 8-hydroxy-DHK, corresponding to the monomeric unit of ACT. Further metabolite analysis identified its related compound, clearly derived from the reduction of 8-hydroxy-DHK. The structures of these metabolites indicate the essential role of ActVA-ORF4 in ACT biosynthesis, specifically in dimerization of a BIQ intermediate via C-C bond formation.
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actinoperylone a novel perylenequinone type shunt product from a Deletion Mutant of the actva orf5 and orf6 genes for actinorhodin biosynthesis in streptomyces coelicolor a3 2
Tetrahedron Letters, 2008Co-Authors: Takaaki Taguchi, Yutaka Ebizuka, Kozo Ochi, Susumu Okamoto, Takayuki Itoh, Koji IchinoseAbstract:A novel shunt product, actinoperylone, has been isolated from a Deletion Mutant of the actVA-ORF5 and ORF6 genes involved in the biosynthesis of a benzoisochromanequinone (BIQ) antibiotic actinorhodin (ACT) in Streptomyces coelicolor A3(2). Spectroscopic analysis revealed its perylenequinone-type skeleton with the four chiral centers, obviously derived from the dimerization of an ACT intermediate. The structure of actinoperylone indicates the essential role of ActVA-ORF5 in the oxygen introduction at C-6, which is common to the formation of BIQ chromophore. The present results also agree with the distribution of the actVA-ORF5 homologues in all known BIQ biosynthetic clusters in streptomycetes.
Javier G Fernandezvelasco - One of the best experts on this subject based on the ideXlab platform.
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electron transfer and stability of the cytochrome b6f complex in a small domain Deletion Mutant of cytochrome f
Journal of Biological Chemistry, 2001Co-Authors: Xiao-song Gong, Susana Chung, Javier G FernandezvelascoAbstract:The lumen segment of cytochrome f consists of a small and a large domain. The role of the small domain in the biogenesis and stability of the cytochrome b(6)f complex and electron transfer through the cytochrome b(6)f complex was studied with a small domain Deletion Mutant in Chlamydomonas reinhardtii. The Mutant is able to grow photoautotrophically but with a slower rate than the wild type strain. The heme group is covalently attached to the polypeptide, and the visible absorption spectrum of the Mutant protein is identical to that of the native protein. The kinetics of electron transfer in the Mutant were measured by flash kinetic spectroscopy. Our results show that the rate for the oxidation of cytochrome f was unchanged (t(12) = approximately 100 micros), but the half-time for the reduction of cytochrome f is increased (t(12) = 32 ms; for wild type, t(12) = 2.1 ms). Cytochrome b(6) reduction was slower than that of the wild type by a factor of approximately 2 (t(12) = 8.6 ms; for wild type, t(12) = 4.7 ms); the slow phase of the electrochromic band shift also displayed a slower kinetics (t(12) = 5.5 ms; for wild type, t(12) = 2.7 ms). The stability of the cytochrome b(6)f complex in the Mutant was examined by following the kinetics of the degradation of the individual subunits after inhibiting protein synthesis in the chloroplast. The results indicate that the cytochrome b(6)f complex in the small domain Deletion Mutant is less stable than in the wild type. We conclude that the small domain is not essential for the biogenesis of cytochrome f and the cytochrome b(6)f complex. However, it does have a role in electron transfer through the cytochrome b(6)f complex and contributes to the stability of the complex.
Javier G. Fernández-velasco - One of the best experts on this subject based on the ideXlab platform.
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Electron transfer and stability of the cytochrome b6f complex in a small domain Deletion Mutant of cytochrome f.
Journal of Biological Chemistry, 2001Co-Authors: Xiao-song Gong, Susana Chung, Javier G. Fernández-velascoAbstract:Abstract The lumen segment of cytochrome fconsists of a small and a large domain. The role of the small domain in the biogenesis and stability of the cytochromeb 6 f complex and electron transfer through the cytochrome b 6 f complex was studied with a small domain Deletion Mutant in Chlamydomonas reinhardtii. The Mutant is able to grow photoautotrophically but with a slower rate than the wild type strain. The heme group is covalently attached to the polypeptide, and the visible absorption spectrum of the Mutant protein is identical to that of the native protein. The kinetics of electron transfer in the Mutant were measured by flash kinetic spectroscopy. Our results show that the rate for the oxidation of cytochrome f was unchanged (t = ∼100 μs), but the half-time for the reduction of cytochrome f is increased (t = 32 ms; for wild type,t = 2.1 ms). Cytochromeb 6 reduction was slower than that of the wild type by a factor of approximately 2 (t = 8.6 ms; for wild type, t = 4.7 ms); the slow phase of the electrochromic band shift also displayed a slower kinetics (t = 5.5 ms; for wild type,t = 2.7 ms). The stability of the cytochromeb 6 f complex in the Mutant was examined by following the kinetics of the degradation of the individual subunits after inhibiting protein synthesis in the chloroplast. The results indicate that the cytochromeb 6 f complex in the small domain Deletion Mutant is less stable than in the wild type. We conclude that the small domain is not essential for the biogenesis of cytochromef and the cytochromeb 6 f complex. However, it does have a role in electron transfer through the cytochromeb 6 f complex and contributes to the stability of the complex.
Christoph Wittmann - One of the best experts on this subject based on the ideXlab platform.
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superior production of heavy pamamycin derivatives using a bkdr Deletion Mutant of streptomyces albus j1074 r2
Microbial Cell Factories, 2021Co-Authors: Lars Glaser, Martin Kuhl, Julian Stegmuller, Christian Ruckert, Maksym Myronovskyi, Jorn Kalinowski, Andriy Luzhetskyy, Christoph WittmannAbstract:Background Pamamycins are macrodiolides of polyketide origin which form a family of differently large homologues with molecular weights between 579 and 663. They offer promising biological activity against pathogenic fungi and gram-positive bacteria. Admittedly, production titers are very low, and pamamycins are typically formed as crude mixture of mainly smaller derivatives, leaving larger derivatives rather unexplored so far. Therefore, strategies that enable a more efficient production of pamamycins and provide increased fractions of the rare large derivatives are highly desired. Here we took a systems biology approach, integrating transcription profiling by RNA sequencing and intracellular metabolite analysis, to enhance pamamycin production in the heterologous host S. albus J1074/R2. Results Supplemented with L-valine, the recombinant producer S. albus J1074/R2 achieved a threefold increased pamamycin titer of 3.5 mg L-1 and elevated fractions of larger derivatives: Pam 649 was strongly increased, and Pam 663 was newly formed. These beneficial effects were driven by increased availability of intracellular CoA thioesters, the building blocks for the polyketide, resulting from L-valine catabolism. Unfavorably, L-valine impaired growth of the strain, repressed genes of mannitol uptake and glycolysis, and suppressed pamamycin formation, despite the biosynthetic gene cluster was transcriptionally activated, restricting production to the post L-valine phase. A Deletion Mutant of the transcriptional regulator bkdR, controlling a branched-chain amino acid dehydrogenase complex, revealed decoupled pamamycin biosynthesis. The regulator Mutant accumulated the polyketide independent of the nutrient status. Supplemented with L-valine, the novel strain enabled the biosynthesis of pamamycin mixtures with up to 55% of the heavy derivatives Pam 635, Pam 649, and Pam 663: almost 20-fold more than the wild type. Conclusions Our findings open the door to provide rare heavy pamamycins at markedly increased efficiency and facilitate studies to assess their specific biological activities and explore this important polyketide further.