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Information on EC 2.5.1.103 - presqualene diphosphate synthase
for references in articles please use BRENDA:EC2.5.1.103
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EC Tree 2 Transferases
2.5 Transferring alkyl or aryl groups, other than methyl groups
2.5.1 Transferring alkyl or aryl groups, other than methyl groups (only sub-subclass identified to date)
2.5.1.103 presqualene diphosphate synthase
IUBMB Comments
Isolated from the green alga Botryococcus braunii BOT22. Unlike EC 2.5.1.21, squalene synthase, where squalene is formed in one step from farnesyl diphosphate, in this alga the intermediate presqualene diphosphate is generated and released by this enzyme. This compound is then converted into either squalene (by EC 1.3.1.96, Botryococcus squalene synthase) or botryococcene (EC 1.3.1.97, botryococcene synthase).
The expected taxonomic range for this enzyme is: Eukaryota, Bacteria
- 2.5.1.103
- botryococcus
- braunii
- botryococcene
-
microalga
-
triterpene
showSynonyms
ssl-1, squalene synthase-like, more
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
squalene synthase
squalene synthase-like 1
squalene synthase-like enzyme
SSL-1
SSL-2
SSL-1
-
-
-
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
2 (2E,6E)-farnesyl diphosphate = presqualene diphosphate + diphosphate
-
-
-
-
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PATHWAY SOURCE
PATHWAYS
MetaCyc
4,4'-diapolycopenedioate biosynthesis, botryococcenes and methylated squalene biosynthesis, epoxysqualene biosynthesis, hopanoid biosynthesis (bacteria), staphyloxanthin biosynthesis
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SYSTEMATIC NAME
IUBMB Comments
(2E,6E)-farnesyl-diphosphate:(2E,6E)-farnesyl-diphosphate farnesyltransferase (presqualene diphosphate forming)
Isolated from the green alga Botryococcus braunii BOT22. Unlike EC 2.5.1.21, squalene synthase, where squalene is formed in one step from farnesyl diphosphate, in this alga the intermediate presqualene diphosphate is generated and released by this enzyme. This compound is then converted into either squalene (by EC 1.3.1.96, Botryococcus squalene synthase) or botryococcene (EC 1.3.1.97, botryococcene synthase).
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 (2E,6E)-farnesyl diphosphate + NADPH + H+
diphosphate + presqualene diphosphate + NADP+
Substrates: -
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
Substrates: -
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
Substrates: condensation of two molecules of farnesyl diphosphate
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
-
Substrates: reaction of enzyme forms squalene synthase and SSL-1
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
-
Substrates: reaction of enzyme forms squalene synthase and SSL-1
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
-
Substrates: reaction of isoform SSL-1
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
-
Substrates: reaction of isoform SSL-1
Products: -
Products: -
?
2 geranylgeranyl diphosphate
lycopaoctaene + 2 diphosphate
-
Substrates: reaction of enzyme form SSL-2
Products: -
Products: -
?
2 geranylgeranyl diphosphate
lycopaoctaene + 2 diphosphate
-
Substrates: reaction of enzyme form SSL-2
Products: -
Products: -
?
presqualene diphosphate + NADPH + H+
squalene + NADP+ + diphosphate
-
Substrates: reaction of enzyme form SSL-2
Products: -
Products: -
?
presqualene diphosphate + NADPH + H+
squalene + NADP+ + diphosphate
-
Substrates: reaction of enzyme form SSL-2
Products: -
Products: -
?
additional information
?
-
Substrates: no synthesis of squalene from presqualene diphosphate, analysis of substrate specificity, overview
Products: -
Products: -
?
additional information
?
-
-
Substrates: no synthesis of squalene from presqualene diphosphate, analysis of substrate specificity, overview
Products: -
Products: -
?
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 (2E,6E)-farnesyl diphosphate + NADPH + H+
diphosphate + presqualene diphosphate + NADP+
Substrates: -
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
Substrates: -
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
-
Substrates: reaction of enzyme forms squalene synthase and SSL-1
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
-
Substrates: reaction of enzyme forms squalene synthase and SSL-1
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
-
Substrates: reaction of isoform SSL-1
Products: -
Products: -
?
2 (2E,6E)-farnesyl diphosphate
presqualene diphosphate + diphosphate
-
Substrates: reaction of isoform SSL-1
Products: -
Products: -
?
2 geranylgeranyl diphosphate
lycopaoctaene + 2 diphosphate
-
Substrates: reaction of enzyme form SSL-2
Products: -
Products: -
?
2 geranylgeranyl diphosphate
lycopaoctaene + 2 diphosphate
-
Substrates: reaction of enzyme form SSL-2
Products: -
Products: -
?
presqualene diphosphate + NADPH + H+
squalene + NADP+ + diphosphate
-
Substrates: reaction of enzyme form SSL-2
Products: -
Products: -
?
presqualene diphosphate + NADPH + H+
squalene + NADP+ + diphosphate
-
Substrates: reaction of enzyme form SSL-2
Products: -
Products: -
?
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
Highest Expressing Human Cell Lines
Cell Line LinksPlease wait a moment until the data is sorted. This message will disappear when the data is sorted.
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
evolution
SSL_1 belongs to the family of squalene synthase-like enzymes. Triterpene metabolism in Botryococcus braunii operates differently from that in other organisms. While squalene synthase, an ancient and likely progenitor to the other Botryococcus triterpene synthases, catalyzes a two-step reaction within a single enzyme unit without intermediate release, yet in Botryococcus braunii, these activities appear to have separated and evolved interdependently for specialized greater triterpene oil production into SSL-1 an SSL-2
metabolism
additional information
metabolism
SSL-1 catalyzes the biosynthesis of presqualene diphosphate. The product presqualene diphosphate is further converted to botryococcene by SSL-3 or to squalene by SSL-2.. While squalene synthase, an ancient and likely progenitor to the other Botryococcus triterpene synthases, catalyzes a two-step reaction within a single enzyme unit without intermediate release, yet in Botryococcus braunii, these activities appear to have separated and evolved interdependently for specialized greater triterpene oil production
metabolism
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, overview
additional information
bisfarnesyl ether biosynthesis from (2E,6E)-farnesyl diphosphate by SSL-2, overview
additional information
-
bisfarnesyl ether biosynthesis from (2E,6E)-farnesyl diphosphate by SSL-2, overview
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
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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). PSDS_BOTBR
403
0
45953
Swiss-Prot
other Location (Reliability: 5)
HPND_ZYMMO
Zymomonas mobilis subsp. mobilis (strain ATCC 31821 / ZM4 / CP4)
291
0
32577
Swiss-Prot
-
HPND_SINFN
Sinorhizobium fredii (strain NBRC 101917 / NGR234)
279
0
31354
Swiss-Prot
-
HPND_RHOPA
Rhodopseudomonas palustris (strain ATCC BAA-98 / CGA009)
279
0
30906
Swiss-Prot
-
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SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Y175A
site-sirected mutagenesis, mutant substrate specificity and activity compared to the wild-type
Y175F
site-sirected mutagenesis, mutant substrate specificity and activity compared to the wild-type
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
gene SSL-1, sequence comparisons, recombinant expression of wild-type and mutant enzymes in Escherichia coli strain BL21(DE3)
screening for squalene synthase-like genes, identification of gene SSL-1, DNA and amino acid sequence determmination and analysis, co-expression with SSL-2 leads to30fold increased squalene production
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REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Niehaus, T.D.; Okada, S.; Devarenne, T.P.; Watt, D.S.; Sviripa, V.; Chappell, J.
Identification of unique mechanisms for triterpene biosynthesis in Botryococcus braunii
Proc. Natl. Acad. Sci. USA
108
12260-12265
2011
Botryococcus braunii (G0Y286), Botryococcus braunii
brenda
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 (G0Y286), Botryococcus braunii
brenda
Thapa, H.R.; Naik, M.T.; Okada, S.; Takada, K.; Molnar, I.; Xu, Y.; Devarenne, T.P.
A squalene synthase-like enzyme initiates production of tetraterpenoid hydrocarbons in Botryococcus braunii Race L
Nat. Commun.
7
11198
2016
Botryococcus braunii, Botryococcus braunii Race L
brenda
Hsu, S.; Browne, D.; Tatli, M.; Devarenne, T.; Stern, D.
N-terminal sequences affect expression of triterpene biosynthesis enzymes in Chlamydomonas chloroplasts
Algal Res.
44
101662
2019
Chlamydomonas reinhardtii, Chlamydomonas reinhardtii CC-125
-
brenda
EXTERNAL LINKS (specific for EC-Number 2.5.1.103)
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Release 2026.1 (March 2026)
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