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discounted EARLY registration ends Dec 31, 2014
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discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
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MetaCyc Enzyme: geosmin synthase / octalin synthase / germacradienol synthase

Gene: cyc2 Accession Number: G-10710 (MetaCyc)

Synonyms: SCO6073

Species: Streptomyces coelicolor

Summary:
The cyc2 gene of Streptomyces coelicolor was found based on its similarity to the Streptomyces exfoliatus gene encoding pentalenene synthase (see EC 4.2.3.7). The gene was cloned and expressed to high levels in Escherichia coli, and the protein was shown to catalyze the Mg2+-dependent conversion of (2E,6E)-farnesyl diphosphate to (1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol, also producing small amounts of (-)-germacrene D and (8S,9S,10S)-8,10-dimethyl-1-octalin. Further analysis demonstrated that the N-terminal part of the protein was sufficient for catalyzing this reaction [Cane03].

Additional work found that the enzyme was also capable of catalyzing the transformation of (1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol to (-)-geosmin. This reaction was catalyzed by the C-terminal part of the protein [Jiang06a]. The functionally independent domains are joined by a ~50-amino acid residue linker. The (1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol that is created by the N-terninal domain diffuses to the C-terminal domain, where it is transformed into (-)-geosmin.

Gene Citations: [Gust03]

Molecular Weight of Polypeptide: 81.474 kD (from nucleotide sequence)

Unification Links: Entrez-gene:1101514 , Protein Model Portal:Q9X839 , String:100226.SCO6073 , UniProt:Q9X839

Relationship Links: InterPro:IN-FAMILY:IPR005630 , InterPro:IN-FAMILY:IPR008949 , Pfam:IN-FAMILY:PF03936

Gene-Reaction Schematic: ?

Credits:
Created 09-Jun-2008 by Caspi R , SRI International


Enzymatic reaction of: geosmin synthase

(8S,9S,10S)-8,10-dimethyl-1-octalin + H2O <=> (-)-geosmin

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: geosmin biosynthesis

Activators (Allosteric): Mg2+ [Jiang06a]


Enzymatic reaction of: octalin synthase

(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol <=> (8S,9S,10S)-8,10-dimethyl-1-octalin + acetone

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: geosmin biosynthesis


Enzymatic reaction of: germacradienol synthase

EC Number: 4.2.3.22

(2E,6E)-farnesyl diphosphate + H2O <=> (1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + diphosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: geosmin biosynthesis

Activators (Allosteric): Mg2+ [Cane03]

Kinetic Parameters:

Substrate
Km (μM)
Citations
(2E,6E)-farnesyl diphosphate
62.0
[Cane03]


References

Cane03: Cane DE, Watt RM (2003). "Expression and mechanistic analysis of a germacradienol synthase from Streptomyces coelicolor implicated in geosmin biosynthesis." Proc Natl Acad Sci U S A 100(4);1547-51. PMID: 12556563

Gust03: Gust B, Challis GL, Fowler K, Kieser T, Chater KF (2003). "PCR-targeted Streptomyces gene replacement identifies a protein domain needed for biosynthesis of the sesquiterpene soil odor geosmin." Proc Natl Acad Sci U S A 100(4);1541-6. PMID: 12563033

Jiang06a: Jiang J, He X, Cane DE (2006). "Geosmin biosynthesis. Streptomyces coelicolor germacradienol/germacrene D synthase converts farnesyl diphosphate to geosmin." J Am Chem Soc 128(25);8128-9. PMID: 16787064


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Wed Nov 26, 2014, biocyc13.