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Information on EC 2.5.1.21 - squalene synthase and Organism(s) Botryococcus braunii and UniProt Accession Q9SDW9
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2.5.1.21 squalene synthaseIUBMB Comments
This microsomal enzyme catalyses the first committed step in the biosynthesis of sterols. The enzyme from yeast requires either Mg2+ or Mn2+ for activity. In the absence of NAD(P)H, presqualene diphosphate (PSPP) is accumulated. When NAD(P)H is present, presqualene diphosphate does not dissociate from the enzyme during the synthesis of squalene from farnesyl diphosphate (FPP) . High concentrations of FPP inhibit the production of squalene but not of PSPP .
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Word Map
- 2.5.1.21
-
farnesylation
- cholesterol
-
prenylation
- sterol
- ftase
- mevalonate
-
geranylgeranylation
-
isoprenoids
- leukemia
-
geranylgeranyltransferase
- pyrophosphate
- tipifarnib
- hmg-coa
- statin
- h-ras
-
peptidomimetic
-
epoxidase
- prenyltransferase
- dolichols
- rhob
-
isoprenylation
-
triterpene
- farnesol
-
3-hydroxy-3-methylglutaryl
- lamins
- ergosterol
-
cholesterol-lowering
- hmgcr
-
prelamin
-
p21ras
- lovastatin
-
hutchinson-gilford
- lanosterol
- manumycin
-
triterpenoids
- synthesis
-
progerin
-
farnesylpyrophosphate
- cis-prenyltransferase
- drug development
- oxidosqualene
-
ras-transformed
- medicine
-
ras-dependent
-
nonsterols
-
ras-mediated
-
withanolides
- srebp-2
-
ganoderic
- agriculture
- geranylgeraniol
- industry
- cycloartenol
-
non-thiol
- 2,3-oxidosqualene
The taxonomic range for the selected organisms is: Botryococcus braunii
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
Reaction Schemes
hide(Overall reactions are displayed. Show all >>)
Synonyms
farnesyltransferase, squalene synthase, sqs, fdft1, squalene synthetase, farnesyl-diphosphate farnesyltransferase, sgsqs, ssase, sqase, tksqs1, 
more
topSYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
farnesyl-diphosphate farnesyltransferase
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-
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farnesyldiphosphate:farnesyldiphosphate farnesyltransferase
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-
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farnesyltransferase
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-
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presqualene synthase
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-
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presqualene-diphosphate synthase
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-
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squalene synthase
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-
-
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squalene synthetase
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-
-
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synthase, squalene
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-
-
-
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
alkenyl group transfer
-
-
-
-
PATHWAY SOURCE
PATHWAYS
BRENDA
SYSTEMATIC NAME
IUBMB Comments
(2E,6E)-farnesyl-diphosphate:(2E,6E)-farnesyl-diphosphate farnesyltransferase
This microsomal enzyme catalyses the first committed step in the biosynthesis of sterols. The enzyme from yeast requires either Mg2+ or Mn2+ for activity. In the absence of NAD(P)H, presqualene diphosphate (PSPP) is accumulated. When NAD(P)H is present, presqualene diphosphate does not dissociate from the enzyme during the synthesis of squalene from farnesyl diphosphate (FPP) [8]. High concentrations of FPP inhibit the production of squalene but not of PSPP [8].
CAS REGISTRY NUMBER
COMMENTARY
9077-14-9
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 (2E,6E)-farnesyl diphosphate + NADPH + H+
squalene + 2 diphosphate + NADP+
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-
-
?
2 farnesyl diphosphate + NADPH + H+
squalene + 2 diphosphate + NADP+
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-
-
?
presqualene diphosphate + NADPH + H+
squalene + diphosphate + NADP+
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-
-
?
additional information
?
-
squalene and botryococcene are branched-chain, triterpene compounds that arise from the head-to-head condensation of two molecules of farnesyl diphosphate to yield 1'-1 and 1'-3 linkages, respectively. Different enzymes are responsible for botryococcene and squalene biosynthesis in the green alga Botryococcus braunii race B. The specificity for the 1'-1 and 1'-3 linkages is controlled by residues in the active sites that can mediate catalytic specificity. Identification of several amino acid positions contributing to the rearrangement of the cyclopropyl intermediate to squalene, The same positions do not appear to be sufficient to account for the cyclopropyl rearrangement to give botryococcene, oerview
-
-
?
additional information
?
-
-
squalene and botryococcene are branched-chain, triterpene compounds that arise from the head-to-head condensation of two molecules of farnesyl diphosphate to yield 1'-1 and 1'-3 linkages, respectively. Different enzymes are responsible for botryococcene and squalene biosynthesis in the green alga Botryococcus braunii race B. The specificity for the 1'-1 and 1'-3 linkages is controlled by residues in the active sites that can mediate catalytic specificity. Identification of several amino acid positions contributing to the rearrangement of the cyclopropyl intermediate to squalene, The same positions do not appear to be sufficient to account for the cyclopropyl rearrangement to give botryococcene, oerview
-
-
?
additional information
?
-
analysis of substrate specificity, overview
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-
?
additional information
?
-
-
analysis of substrate specificity, overview
-
-
?
NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 (2E,6E)-farnesyl diphosphate + NADPH + H+
squalene + 2 diphosphate + NADP+
-
-
-
?
2 farnesyl diphosphate + NADPH + H+
squalene + 2 diphosphate + NADP+
-
-
-
?
additional information
?
-
squalene and botryococcene are branched-chain, triterpene compounds that arise from the head-to-head condensation of two molecules of farnesyl diphosphate to yield 1'-1 and 1'-3 linkages, respectively. Different enzymes are responsible for botryococcene and squalene biosynthesis in the green alga Botryococcus braunii race B. The specificity for the 1'-1 and 1'-3 linkages is controlled by residues in the active sites that can mediate catalytic specificity. Identification of several amino acid positions contributing to the rearrangement of the cyclopropyl intermediate to squalene, The same positions do not appear to be sufficient to account for the cyclopropyl rearrangement to give botryococcene, oerview
-
-
?
additional information
?
-
-
squalene and botryococcene are branched-chain, triterpene compounds that arise from the head-to-head condensation of two molecules of farnesyl diphosphate to yield 1'-1 and 1'-3 linkages, respectively. Different enzymes are responsible for botryococcene and squalene biosynthesis in the green alga Botryococcus braunii race B. The specificity for the 1'-1 and 1'-3 linkages is controlled by residues in the active sites that can mediate catalytic specificity. Identification of several amino acid positions contributing to the rearrangement of the cyclopropyl intermediate to squalene, The same positions do not appear to be sufficient to account for the cyclopropyl rearrangement to give botryococcene, oerview
-
-
?
COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
squalene synthase consists of both an N-terminal catalytic domain and a C-terminal domain tethering the enzyme to the endoplasmic reticulum membrane
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
metabolism
squalene synthase catalyzes the first committed step in sterol biosynthesis
physiological function
squalene and botryococcene are branched-chain, triterpene compounds that arise from the head-tohead condensation of two molecules of farnesyl diphosphate to yield 1'-1 and 1'-3 linkages, respectively
additional information
additional information
proposed catalytic cascades for the enzyme-mediated biosynthesis of squalene and botryococcene, and molecular modeling of Botryococcus braunii botryococcene and squalene synthase enzymes, overview. Substrate docking and molecular modeling
additional information
-
proposed catalytic cascades for the enzyme-mediated biosynthesis of squalene and botryococcene, and molecular modeling of Botryococcus braunii botryococcene and squalene synthase enzymes, overview. Substrate docking and molecular modeling
UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable).
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable). BSS_BOTBR
461
1
52547
Swiss-Prot
other Location (Reliability: 2)
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
squalene synthase consists of both an N-terminal catalytic domain and a C-terminal domain tethering the enzyme to the endoplasmic reticulum membrane
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
A177N
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
A177N/Q213G
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type, the mutant has lost the first reaction step but retains a greater level of the second reaction step for the conversion of presqualene diphosphate to squalene
D220A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
D224A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
D79A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
D83A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
E223A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
E82A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
G207Q
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
N171A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
Q213G
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
Q213N
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
R219A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
R76A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
V176N
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
V176N/A177N
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
Y172A
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
Y172F
site-directed mutagenesis, mutant substrate specificity and activity compared to the wild-type
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
gene BbSS, sequence comparisons, recombinant expression of C-terminally truncated wild-type and mutant enzymes BbSS, lacking 65 amino acids, in Escherichia coli strain BL21(DE3)
gene BSS, recombinant enzyme expression in an enzyme-deficient SQS-knockout Saccharomyces cerevisiae DELTAerg9 strain, the enzyme can partially complement the knockout mutation when the gene is weakly expressed, but when highly expressed, the non-fungal squalene synthase cannot complement the yeast mutation and instead leads to the accumulation of a toxic intermediate(s) as defined by mutations of genes downstream in the ergosterol pathway
heterologous expression of a squalene synthase from Botryocuccus braunii can increase squalene accumulation in a DELTAshc strain of Synechocystis
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Okada, S.; Devarenne, T.P.; Chappell, J.
Molecular characterization of squalene synthase from the green microalga Botryococcus braunii, race B
Arch. Biochem. Biophys.
373
307-317
2000
Botryococcus braunii (Q9SDW9), Botryococcus braunii
Linscott, K.B.; Niehaus, T.D.; Zhuang, X.; Bell, S.A.; Chappell, J.
Mapping a kingdom-specific functional domain of squalene synthase
Biochim. Biophys. Acta
1861
1049-1057
2016
Arabidopsis thaliana, Homo sapiens (P37268), Saccharomyces cerevisiae (P53866), Saccharomyces cerevisiae, Botryococcus braunii (Q9SDW9)
Bell, S.A.; Niehaus, T.D.; Nybo, S.E.; Chappell, J.
Structure-function mapping of key determinants for hydrocarbon biosynthesis by squalene and squalene synthase-like enzymes from the green alga Botryococcus braunii race B
Biochemistry
53
7570-7581
2014
Botryococcus braunii (Q9SDW9), Botryococcus braunii
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