Cloned (Comment) | Organism |
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gene cyc2, recombinant expression of C-terminally His6-tagged full-length enzyme and of the N-terminal domain of ScGS (residues 1-366) in Escherichia coli strain BL21(DE3)pLysS , subcloning in Escherichia coli strain XL-1 Blue | Streptomyces coelicolor |
Crystallization (Comment) | Organism |
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purified recombinant N-terminal domain of ScGS, unliganded and in complex with 3 Mg2+ ions and alendronate, mixing of 600 nl of 7 mg/ml protein in 25 mM Tris, pH 8.2, 5 mM MgCl2, 10 mM BME, and 1.5 mM sodium alendronate, with 600 nl of precipitant solution containing 0.2 M sodium acetate trihydrate, pH 7.0, and 20% w/v PEG 3350, and equilibration against 0.1 ml of reservoir solution at room temperature, X-ray diffraction structure determination and analysis at 2.4 A resolution. Neither full-length ScGS nor constructs of the C-terminal domain can be crystallized, but homology models of the C-terminal domain are constructed based on about 36% sequence identity with the N-terminal domain | Streptomyces coelicolor |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | each enzyme domain requires Mg2+ for catalysis, binding structure analysis at the N-terminal domain, overview | Streptomyces coelicolor |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + H2O | Streptomyces coelicolor | - |
(-)-geosmin + acetone | - |
? | |
(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + H2O | Streptomyces coelicolor ATCC BAA-471 / A3(2) / M145 | - |
(-)-geosmin + acetone | - |
? | |
additional information | Streptomyces coelicolor | geosmin synthase is a bifunctional sesquiterpene synthase with alpha-alpha domain architecture that catalyzes a unique cyclization fragmentation reaction sequence | ? | - |
? | |
additional information | Streptomyces coelicolor ATCC BAA-471 / A3(2) / M145 | geosmin synthase is a bifunctional sesquiterpene synthase with alpha-alpha domain architecture that catalyzes a unique cyclization fragmentation reaction sequence | ? | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Streptomyces coelicolor | Q9X839 | - |
- |
Streptomyces coelicolor ATCC BAA-471 / A3(2) / M145 | Q9X839 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant C-terminally His6-tagged full-length enzyme from Escherichia coli strain BL21(DE3)pLysS by nickel affinity chromatography, recombinant N-terminal domain of ScGS (residues 1-366) from Escherichia coli strain BL21(DE3)pLysS by ammonium sulfate fractionation, adsorption chromatography on methyl resin, gel filtration, and ultrafiltartion | Streptomyces coelicolor |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + H2O = (-)-geosmin + acetone | the active site in the N-terminal domain of enzyme ScGS catalyzes the ionization-dependent cyclization of FPP to form diphosphate and two cyclic products: germacradienol (major product, 85%) and germacrene D (minor product, 15%). After dissociation from the N-terminal domain, germacradienol is rebound to the active site of the C-terminal domain where it is converted to geosmin in a protonation-dependent cyclization reaction accompanied by the elimination of acetone through a retro-Prins reaction. The tandem cyclization-fragmentation reactions catalyzed by ScGS require two distinct active sites, a unique alphaalpha domain architecture is predicted for ScGS based on primary structure analysis | Streptomyces coelicolor |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + H2O | - |
Streptomyces coelicolor | (-)-geosmin + acetone | - |
? | |
(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + H2O | - |
Streptomyces coelicolor ATCC BAA-471 / A3(2) / M145 | (-)-geosmin + acetone | - |
? | |
additional information | geosmin synthase is a bifunctional sesquiterpene synthase with alpha-alpha domain architecture that catalyzes a unique cyclization fragmentation reaction sequence | Streptomyces coelicolor | ? | - |
? | |
additional information | geosmin synthase from Streptomyces coelicolor (ScGS) catalyzes an unusual, metal-dependent terpenoid cyclization and fragmentation reaction sequence. Two distinct active sites are required for catalysis: the N-terminal domain catalyzes the ionization and cyclization of farnesyl diphosphate to form germacradienol and inorganic pyrophosphate (PPi), and the C-terminal domain catalyzes the protonation, cyclization, and fragmentation of germacradienol to form geosmin and acetone through a retro-Prins reaction. The enzyme has an alpha,alpha domain architecture, each domain contains the metal-binding motifs typical of a class I terpenoid cyclase, and each domain requires Mg2+ for catalysis. There is no direct channel for transfer of the intermediate from the active site of the N-terminal domain to that of the C-terminal domain. It is a diiffusive transfer of the germacradienol intermediate | Streptomyces coelicolor | ? | - |
? | |
additional information | geosmin synthase is a bifunctional sesquiterpene synthase with alpha-alpha domain architecture that catalyzes a unique cyclization fragmentation reaction sequence | Streptomyces coelicolor ATCC BAA-471 / A3(2) / M145 | ? | - |
? | |
additional information | geosmin synthase from Streptomyces coelicolor (ScGS) catalyzes an unusual, metal-dependent terpenoid cyclization and fragmentation reaction sequence. Two distinct active sites are required for catalysis: the N-terminal domain catalyzes the ionization and cyclization of farnesyl diphosphate to form germacradienol and inorganic pyrophosphate (PPi), and the C-terminal domain catalyzes the protonation, cyclization, and fragmentation of germacradienol to form geosmin and acetone through a retro-Prins reaction. The enzyme has an alpha,alpha domain architecture, each domain contains the metal-binding motifs typical of a class I terpenoid cyclase, and each domain requires Mg2+ for catalysis. There is no direct channel for transfer of the intermediate from the active site of the N-terminal domain to that of the C-terminal domain. It is a diiffusive transfer of the germacradienol intermediate | Streptomyces coelicolor ATCC BAA-471 / A3(2) / M145 | ? | - |
? |
Subunits | Comment | Organism |
---|---|---|
More | geosmin synthase has alpha-alpha domain architecture. The N-terminal domain and the C-terminal domain are separated by a 41-residue linker and share 28% and 29% amino acid sequence identity, respectively, with pentalenene synthase. Each domain contains characteristic metal ion-binding motifs of class I terpenoid cyclases. The aspartate-rich motif is found as D86DHFLE91 and D455DYYP459, and the NSE/DTE motif is found as N229DLFSYQRE237 and N598DVFSYQKE606. The C-terminal domain is also predicted to adopt an alpha fold homologous to that of the N-terminal domain based on approximately 36% amino acid sequence identity between these domains. Primary, secondary and quarternary enzyme structrue analysis, and homology modeling, overview | Streptomyces coelicolor |
Synonyms | Comment | Organism |
---|---|---|
Cyc2 | - |
Streptomyces coelicolor |
ScGS | - |
Streptomyces coelicolor |
General Information | Comment | Organism |
---|---|---|
additional information | neither full-length ScGS nor constructs of the C-terminal domain can be crystallized, but homology models of the C-terminal domain are constructed based on about 36% sequence identity with the N-terminal domain, analysis of the crystal structure of the N-terminal domain in unliganded or liganded form, overview. Possible alpha,alpha domain architectures as frameworks for bifunctional catalysis | Streptomyces coelicolor |
physiological function | geosmin is a powerful odorant with an extremely low human detection threshold of less than 10 parts-per-trillion, and is mainly responsible for the characteristic odor of freshly turned earth. Although geosmin contributes to the pleasant, earthy flavor of beets, it is also a commonly occurring contaminant of musty-tasting water, wine, and fish. Geosmin is not known to cause human disease, but its detection and elimination from potable water sources is a critical environmental and water quality issue | Streptomyces coelicolor |