Information on EC 4.1.99.16 - geosmin synthase

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The expected taxonomic range for this enzyme is: Bacteria

EC NUMBER
COMMENTARY
4.1.99.16
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RECOMMENDED NAME
GeneOntology No.
geosmin synthase
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + H2O = (-)-geosmin + acetone
show the reaction diagram
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(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + H2O = (-)-geosmin + acetone
show the reaction diagram
conversion of germacradienol to geosmin results in the release of the three-carbon side chain as acetone and involves a 1,2-hydride shift of the bridgehead hydrogen exclusively into ring B of geosmin
Q9X839
PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
Biosynthesis of secondary metabolites
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geosmin biosynthesis
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Sesquiterpenoid and triterpenoid biosynthesis
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SYSTEMATIC NAME
IUBMB Comments
germacradienol geosmin-lyase (acetone forming)
Requires Mg2+. Geosmin is the cause of the characteristic smell of moist soil. It is a bifunctional enzyme. The N-terminal part of the enzyme is EC 4.2.3.22, germacradienol synthase, and forms germacradienol from FPP. The C-terminal part of the enzyme catalyses the conversion of germacradienol to geosmin via (1S,4aS,8aS)-1,4a-dimethyl-1,2,3,4,4a,5,6,8a-octahydronaphthalene.
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
i.e. ANA318, isolated at the Australian Water Quality Centre in 1995 from a sample sourced from Pejar Dam in Goulburn, NSW, Australia, during a taste and odor episode
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Manually annotated by BRENDA team
i.e. ANA318, isolated at the Australian Water Quality Centre in 1995 from a sample sourced from Pejar Dam in Goulburn, NSW, Australia, during a taste and odor episode
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Manually annotated by BRENDA team
germacradienol/geosmin synthase
UniProt
Manually annotated by BRENDA team
C-terminal domain; germacradienol/germacrene D synthase
UniProt
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
physiological function
B0F2N6
deletion of the doxorubicin gene cluster results in increased cell growth rate along with detectable production of geosmin. Overexpression of the spterp13 gene in the Streptomyecs peucetius doxorubicin mutant leads to 2.4fold enhanced production of geosmin
physiological function
Q82L49
mutants with a deleted geoA are unable to produce either germacradienol or geosmin
physiological function
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deletion of the doxorubicin gene cluster results in increased cell growth rate along with detectable production of geosmin. Overexpression of the spterp13 gene in the Streptomyecs peucetius doxorubicin mutant leads to 2.4fold enhanced production of geosmin
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additional information
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geosmin synthesis (and geosmin synthase expression) appears to be coordinated with cell growth
additional information
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geosmin synthesis (and geosmin synthase expression) appears to be coordinated with cell growth
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SUBSTRATE
PRODUCT                      
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + H2O
(-)-geosmin + acetone
show the reaction diagram
Q9X839
catalysed by the C-terminal domain of the bifunctional enzyme
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?
(2E,6E)-farnesyl diphosphate + H2O
(4S,7R)-germacra-1(10)E,5E-diene-11-ol + (7S)-germacrene D + geosmin + ?
show the reaction diagram
Q82L49
overall reaction of germacradienol/geosmin synthase
presence of Mg2+, synthesis of 66% (4S,7R)-germacra-1(10)E,5E-diene-11-ol, 24% (7S)-germacrene D, 8% geosmin, and 2% of a hydrocarbon, tentatively assigned the structure of octalin
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?
additional information
?
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Q9X839
conversion of germacradienol to geosmin results in the release of the three-carbon side chain as acetone and involves a 1,2-hydride shift of the bridgehead hydrogen exclusively into ring B of geosmin
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additional information
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Q82L49
nerolidyl diphosphate is excluded as an intermediate in the enzymatic formation of germacradienol, germacrene D, and geosmin
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Co2+
Q82L49
10-20% of the activity with Mg2+
Cu2+
Q82L49
10-20% of the activity with Mg2+
Fe2+
Q82L49
50% of the activity with Mg2+
Mg2+
Q82L49
preferred divalent cation, maximum activity at 10 mM
Zn2+
Q82L49
50% of the activity with Mg2+
Mn2+
Q82L49
10-20% of the activity with Mg2+
additional information
Q82L49
absolute requirement for a divalent cation. No activity with Ni2+ or Ca2+
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.000075
(2E,6E)-farnesyl diphosphate
Q82L49
pH 8.2, 30°C
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.0031
(2E,6E)-farnesyl diphosphate
Q82L49
pH 8.2, 30°C
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
7.6 - 9
Q82L49
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
additional information
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relative enzyme expression analysis, enzyme expression under conditions of continuous light illumination and the removal of light as a stimulus appears to be constitutive, the decrease in geosmin synthase transcription post maximum cell numbers and stationary phase suggests that a decrease in isoprenoid synthesis may occur before a decrease in the transcription of ribosomal units as the process of cell death is initiated
Manually annotated by BRENDA team
additional information
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relative enzyme expression analysis, enzyme expression under conditions of continuous light illumination and the removal of light as a stimulus appears to be constitutive, the decrease in geosmin synthase transcription post maximum cell numbers and stationary phase suggests that a decrease in isoprenoid synthesis may occur before a decrease in the transcription of ribosomal units as the process of cell death is initiated
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Manually annotated by BRENDA team
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
relative enzyme expression analysis
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expression in Escherichia coli
Q82L49