The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Kwangkyoung Liou - One of the best experts on this subject based on the ideXlab platform.
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characterization of cyp166b1 and its electron transfer system in streptomyces peucetius var caesius atcc 27952
Enzyme and Microbial Technology, 2010Co-Authors: Pramod Shrestha, Narayan Prasad Niraula, Taejin Oh, Kwangkyoung Liou, Jae Kyung SohngAbstract:Although many Ferredoxins and Ferredoxin reductases have been reported, many details about the homologous electron transfer system of P450s remain unclear. cyp166B1 gene is clustered with the putative Ferredoxin (FDX6) in Streptomyces peucetius var. caesius ATCC 27952. Six Ferredoxin reductases along with the putative Ferredoxin were individually expressed in Escherichia coli and determined the probable primary pathway for dealkylation of 7-ethoxycoumarin as NADH → FDR4 → FDX6 → CYP166B1. Further, mechanistic studies aimed at identifying the endogenous substrate of CYP166B1 would provide a more clear explanation on the homologous electron transfer system.
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genome analyses of streptomyces peucetius atcc 27952 for the identification and comparison of cytochrome p450 complement with other streptomyces
Archives of Biochemistry and Biophysics, 2004Co-Authors: Niranjan Parajuli, Jae Kyung Sohng, Devi B Basnet, Kwangkyoung LiouAbstract:We have determined the genome sequence of 8.7 Mb chromosome of Streptomyces peucetius ATCC 27952, which produces clinically important anthracycline chemotherapeutic agents of the polyketide class of antibiotics, daunorubicin and doxorubicin. The cytochrome P450 (CYP) superfamily is represented by 19 sequences in the S. peucetius. Among those, 15 code for functional genes, whereas the remaining four are pseudo genes. CYPs from S. peucetius are phylogenetically close to those of Streptomyces amermitilis. Four CYPs are associated with modular PKS of avermectin and two with doxorubicin biosynthetic gene cluster. CYP252A1 is the new family found in S. peucetius, which shares 38% identity to CYP51 from Streptomyces coelicolor A3 (2). Nine CYPs from S. peucetius are found in the cluster containing various regulatory genes including rar operon, conserved in S. coelicolor A3 (2) and Streptomyces griseus. Although two Ferredoxins and four Ferredoxin reductases have been identified so far, only one Ferredoxin reductase was found in the cluster of CYP147F1 in S. peucetius. To date, 174 CYPs have been described from 45 Streptomyces species in all searchable databases. However, only 18 CYPs are clustered with Ferredoxin. The comparative study of cytochrome P450s, Ferredoxins, and Ferredoxin reductases should be useful for the future development and manipulation of antibiotic biosynthetic pathways.
F. Inagaki - One of the best experts on this subject based on the ideXlab platform.
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Solution structure of Ferredoxin from the thermophilic cyanobacterium Synechococcus elongatus and its thermostability.
Journal of molecular biology, 1997Co-Authors: Hiroaki Hatanaka, Sadahiro Katoh, R Tanimura, F. InagakiAbstract:The three-dimensional structure of Ferredoxin, purified from the thermophilic cyanobacterium Synechococcus elongatus, was determined in aqueous solution by two-dimensional proton nuclear magnetic resonance. In addition to the 946 distance constraints from nuclear Overhauser effect connectivities, we added 241 distance constraints derived from the crystal structure of Spirulina platensis Ferredoxin to the 19 residues close to the [2Fe-2S] iron-sulfur center, where crosspeaks disappeared due to paramagnetic effects. The atomic root-mean-square difference of the ten converged structures from the mean structure was 0.61(+/-0.12) A for backbone atoms (N, C(alpha), C'). The main-chain structure was almost the same as the crystal structures of other mesophile Ferredoxins, but comparison of the side-chain structures revealed an extension of the hydrophobic core, a unique hydrophobic patch on the surface of the large beta-sheet, and two unique charge networks in this thermostable Ferredoxin structure, some of which might contribute to thermostability.
Tewfik Soulimane - One of the best experts on this subject based on the ideXlab platform.
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New insights into the thermostability of bacterial Ferredoxins: high-resolution crystal structure of the seven-iron Ferredoxin from Thermus thermophilus
JBIC Journal of Biological Inorganic Chemistry, 2001Co-Authors: Sandra Macedo-ribeiro, Berta M. Martins, Pedro Barbosa Pereira, Gerhard Buse, Robert Huber, Tewfik SoulimaneAbstract:The crystal structure of the seven-iron Ferredoxin from Thermus thermophilus (FdTt) has been determined at 1.64 Å resolution, allowing us to unveil the common mechanisms of thermostabilization within "bacterial-type" Ferredoxins. FdTt and other homologous thermophilic seven-iron Ferredoxins are smaller than their mesophilic counterparts. Thermostabilizing features are optimized in a minimal structural and functional unit, with an extensive cross-linking of secondary structure elements mediated by improved polar and hydrophobic interactions. Most of the potentially stabilizing features are focused on the vicinity of the functional [3Fe-4S] cluster. The structural [4Fe-4S] cluster is shielded in thermophilic FdTt by an increased number of polar interactions involving the two N-terminal residues. Comparisons with the hyperthermostable Ferredoxin from Thermotoga maritima reveal that (1) a reduction in the number of non-glycine residues in strained conformations, (2) improved polar interactions within the common iron-sulfur cluster binding (βαβ)_2 motif, and (3) an optimized charge distribution at the protein surface, constitute a common strategy for increasing the thermal stability of these Ferredoxins.
Jae Kyung Sohng - One of the best experts on this subject based on the ideXlab platform.
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characterization of cyp166b1 and its electron transfer system in streptomyces peucetius var caesius atcc 27952
Enzyme and Microbial Technology, 2010Co-Authors: Pramod Shrestha, Narayan Prasad Niraula, Taejin Oh, Kwangkyoung Liou, Jae Kyung SohngAbstract:Although many Ferredoxins and Ferredoxin reductases have been reported, many details about the homologous electron transfer system of P450s remain unclear. cyp166B1 gene is clustered with the putative Ferredoxin (FDX6) in Streptomyces peucetius var. caesius ATCC 27952. Six Ferredoxin reductases along with the putative Ferredoxin were individually expressed in Escherichia coli and determined the probable primary pathway for dealkylation of 7-ethoxycoumarin as NADH → FDR4 → FDX6 → CYP166B1. Further, mechanistic studies aimed at identifying the endogenous substrate of CYP166B1 would provide a more clear explanation on the homologous electron transfer system.
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genome analyses of streptomyces peucetius atcc 27952 for the identification and comparison of cytochrome p450 complement with other streptomyces
Archives of Biochemistry and Biophysics, 2004Co-Authors: Niranjan Parajuli, Jae Kyung Sohng, Devi B Basnet, Kwangkyoung LiouAbstract:We have determined the genome sequence of 8.7 Mb chromosome of Streptomyces peucetius ATCC 27952, which produces clinically important anthracycline chemotherapeutic agents of the polyketide class of antibiotics, daunorubicin and doxorubicin. The cytochrome P450 (CYP) superfamily is represented by 19 sequences in the S. peucetius. Among those, 15 code for functional genes, whereas the remaining four are pseudo genes. CYPs from S. peucetius are phylogenetically close to those of Streptomyces amermitilis. Four CYPs are associated with modular PKS of avermectin and two with doxorubicin biosynthetic gene cluster. CYP252A1 is the new family found in S. peucetius, which shares 38% identity to CYP51 from Streptomyces coelicolor A3 (2). Nine CYPs from S. peucetius are found in the cluster containing various regulatory genes including rar operon, conserved in S. coelicolor A3 (2) and Streptomyces griseus. Although two Ferredoxins and four Ferredoxin reductases have been identified so far, only one Ferredoxin reductase was found in the cluster of CYP147F1 in S. peucetius. To date, 174 CYPs have been described from 45 Streptomyces species in all searchable databases. However, only 18 CYPs are clustered with Ferredoxin. The comparative study of cytochrome P450s, Ferredoxins, and Ferredoxin reductases should be useful for the future development and manipulation of antibiotic biosynthetic pathways.
Barbara K Burgess - One of the best experts on this subject based on the ideXlab platform.
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identification of a palindromic sequence that is responsible for the up regulation of napdh Ferredoxin reductase in a Ferredoxin i deletion strain of azotobacter vinelandii
Journal of Biological Chemistry, 1997Co-Authors: Steven M Yannone, Barbara K BurgessAbstract:Abstract Azotobacter vinelandii Ferredoxin I (AvFdI) is one member of a class of 7Fe Ferredoxins found in a variety of organisms that are all capable of aerobic growth. Disruption of the fdxA gene, which encodesAvFdI, leads to overexpression of its redox partner, NADPH-Ferredoxin reductase (FPR). In this study the mechanism of FdI-mediated regulation of FPR was investigated. Northern analysis has shown that regulation is at the level of fpr transcription, the start site for transcription has been identified, and it is preceded by a canonical ς 70-type bacterial promoter. Gel mobility shift assays show that there is a putative regulatory protein inA. vinelandii that binds specifically upstream of the −35 region. That protein is not AvFdI. A palindromic sequence was identified as a putative binding site, and randomization of that sequence completely eliminates binding of the putative regulatory protein. A luciferase reporter gene was placed under control of theA. vinelandii fpr promoter and introduced into wild type and FdI− strains of A. vinelandii. Luciferase activity was enhanced 7-fold in the FdI− mutant relative to the wild type. Alteration of the palindromic sequence reduced the luciferase levels in the FdI− strain to those of the wild type, demonstrating that FdI regulates FPR through the palindrome and that the reaction is an activation rather than a repression. The identified palindrome is ∼50% identical to the SoxS binding site upstream of Escherichia coli fpr, suggesting that A. vinelandii may have a SoxS-like regulatory system and that the function of FdI might be to specifically inactivate that system.