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Information on EC 5.4.99.17 - squalene-hopene cyclase and Organism(s) Zymomonas mobilis and UniProt Accession P33990
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EC Tree
5.4.99.17 squalene-hopene cyclaseIUBMB Comments
The enzyme also produces the cyclization product hopan-22-ol by addition of water (cf. EC 4.2.1.129, squalene-hopanol cyclase). Hopene and hopanol are formed at a constant ratio of 5:1.
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Word Map
- 5.4.99.17
-
cyclization
- alicyclobacillus
- acidocaldarius
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hopanoids
- cyclases
- oxidosqualene
-
pentacyclic
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triterpene
- 2,3-oxidosqualene
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tetracyclic
- tetrahymanol
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carbocation
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polyolefinic
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5.4.99.7
- lanosterol
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aspartate-rich
- synthesis
The taxonomic range for the selected organisms is: Zymomonas mobilis
The expected taxonomic range for this enzyme is: Bacteria, Archaea, Eukaryota
The expected taxonomic range for this enzyme is: Bacteria, Archaea, Eukaryota
Synonyms
squalene-hopene cyclase, squalene hopene cyclase, aacshc, 
more
topSYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
cyclase, squalene-hopanoid
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SHC
ZmoSHC1
SHC
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-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
squalene = hop-22(29)-ene
catalytic mechanism via Friedel-Crafts alkylation and substrate specificity, overview
squalene = hop-22(29)-ene
catalytic mechanism, the initial reaction catalyzed is the protonation of the terminal double bond of squalene. The conserved DXDD motif of SHCs is essential for this protonation reaction, overview
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
cyclization
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SYSTEMATIC NAME
IUBMB Comments
squalene mutase (cyclizing)
The enzyme also produces the cyclization product hopan-22-ol by addition of water (cf. EC 4.2.1.129, squalene-hopanol cyclase). Hopene and hopanol are formed at a constant ratio of 5:1.
CAS REGISTRY NUMBER
COMMENTARY
76600-69-6
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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
citronellal
isopulegol
activity of mutant F438C, not of the wild-type enzyme
i.e. 2-isopropenyl-5-methyl-cyclohexanol
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?
3,7,11-trimethyldodeca-1,6,10-trien-3-ol
(-)-caparrapioxide + (-)-8-epi-caparrapioxide
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-
-
-
?
farnesyl phenyl ether
(4aS,5S,8aS)-1,1,4a,6-tetramethyl-5-(phenoxymethyl)-1,2,3,4,4a,5,8,8a-octahydronaphthalene + (4aS,4bR,10bR,12aS)-1,1,4a,10b-tetramethyl-2,3,4,4a,4b,5,10b,11,12,12a-decahydro-1H-naphtho[1,2-c]chromene
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-
-
?
geranyl phenyl ether
(6aS,10aS)-7,7,10a-trimethyl-6a,7,8,9,10,10a-hexahydro-6H-benzo[c]chromene
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-
-
?
geranylacetone
(8aS)-2,5,5,8a-tetramethyl-4a,5,6,7,8,8a-hexahydro-4H-chromene
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-
-
-
?
geranylgeranyl phenyl ether
(14b)-8,13-dimethyl-14-(phenoxymethyl)podocarp-12-ene + (14b)-8-methyl-13-methylidene-14-(phenoxymethyl)podocarpane
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-
-
?
citronellal
isopulegol
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i.e. 2-isopropenyl-5-methyl-cyclohexanol
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?
citronellal
isopulegol
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i.e. 2-isopropenyl-5-methyl-cyclohexanol
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?
citronellal
isopulegol
wild-type enzyme, and increased activity in mutant F486C
i.e. 2-isopropenyl-5-methyl-cyclohexanol
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?
squalene
hop-22(29)-ene + hopanol
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the enzyme catalyzes cyclization of the linear triterpenoid squalene to hopene and hopanol by the class II mechanism
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-
?
additional information
?
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no activity with citronellal or isopulegol (2-isopropenyl-5-methyl-cyclohexanol)
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?
additional information
?
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no activity with citronellal or isopulegol (2-isopropenyl-5-methyl-cyclohexanol)
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?
additional information
?
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enzyme produces a wide variety of products due to lack of specificity
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-
?
additional information
?
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no activity with linalool and pseudoionone
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?
additional information
?
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substrate specificity, detailed overview
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?
additional information
?
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substrate specificity, overview. No activity with prenyl phenyl ether
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?
additional information
?
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ZmoSHC1 shows cyclization of the non-natural substrates homofarnesol (C16) and citronellal (C10) in addition to hopene formation from squalene, substrate specificity, overview. ZmoSHC1 exhibits a shift of activity towards substrates of shorter chain lengths, displaying over 50fold higher conversion of homofarnesol and more than 2fold higher conversion of citronellal in comparison to squalene conversion
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-
?
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
citronellal
isopulegol
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i.e. 2-isopropenyl-5-methyl-cyclohexanol
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?
additional information
?
-
no activity with citronellal or isopulegol (2-isopropenyl-5-methyl-cyclohexanol)
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?
additional information
?
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no activity with citronellal or isopulegol (2-isopropenyl-5-methyl-cyclohexanol)
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-
?
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
ethanol
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1.6fold increase of activity when added to the enzyme test system at a concentration of 6%
Propanol
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1.6fold increase of activity when added to the enzyme test system at a concentration of 6%
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
-
enzyme activities in mg/ml of product with different substrates and at different enzyme concentrations, overview
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
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
evolution
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structure-function relationships of squalene-hopene cyclases, the DXDD motif, which is typical for all squalene-hopene cyclases, overview
metabolism
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the enzyme is involved in biosynthesis of hopanoids, members of a large group of cyclic triterpenoic compounds that have important functions in many prokaryotic and eukaryotic organisms
physiological function
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hopene and hopanol are prokaryotic steroid analogues and have important functions as membrane constituents
additional information
additional information
-
structure-function relationships of squalene-hopene cyclases, overview
additional information
the enzyme catalyzes the cyclization of triterpenoids via cationic intermediates in one of the most complex reactions known in biochemistry
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
F438C
site-directed mutagenesis, the mutant performs interconversion of citronellal and isopulegol
F486C
site-directed mutagenesis, the mutant shows increased activity in interconversion of citronellal and isopulegol compared to the wild-type enzyme
W555A
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555C
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555D
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and moderate citronellal cyclase activity
W555E
site-directed mutagenesis, the mutant shows highly reduced squalene hopene cyclase activity, and low citronellal cyclase activity
W555F
W555G
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555H
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and moderate citronellal cyclase activity
W555I
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555K
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555L
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555M
site-directed mutagenesis, the mutant shows highly reduced squalene hopene cyclase activity, and low citronellal cyclase activity
W555N
site-directed mutagenesis, the mutant shows highly reduced squalene hopene cyclase activity, and moderate citronellal cyclase activity
W555P
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555Q
site-directed mutagenesis, the mutant shows highly reduced squalene hopene cyclase activity, and low citronellal cyclase activity
W555R
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555S
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555T
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and higher citronellal cyclase activity
W555V
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and low citronellal cyclase activity
W555Y
W555F
site-directed mutagenesis, the mutant shows no squalene hopene cyclase activity, and higher citronellal cyclase activity
W555F
W555 is essential for hopene formation but W555Y and W555F have enhanced citronellal cyclase activity. All muteins of position W555 show abolished or strongly reduced hopene-forming activity compared to wild-type protein. W555Y is the only mutein with low but significant residual SHC activity
W555Y
site-directed mutagenesis, the mutant shows highly reduced squalene hopene cyclase activity,and higher citronellal cyclase activity
W555Y
W555 is essential for hopene formation but W555Y and W555F have enhanced citronellal cyclase activity. All muteins of position W555 show abolished or strongly reduced hopene-forming activity compared to wild-type protein. W555Y is the only mutein with low but significant residual SHC activity
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
DNA and amino acid sequence determination and analysis, sequence comparison, expression in Escherichia coli strain DH5alpha
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
synthesis
cyclization of homofarnesol to ambroxan as well as the conversion of citronellal to 2-isopropenyl-5-methyl-cyclohexanol bythe isozyme SHC1 can be economically attractive, as both products are used in the flavour and fragrance industry
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Douka, E.; Koukkou, A.; Drainas, C.; Grosdemange-Billiard, C.; Rohmer, M.
Structural diversity of the triterpenic hydrocarbons from the bacterium Zymomonas mobilis: the signature of defective squalene cyclization by the squalene/hopene cyclase
FEMS Microbiol. Lett.
199
247-251
2001
Zymomonas mobilis
Schmidt, A.; Bringer-Meyer, S.; Poralla, K.; Sahm, H.
Influence of ethanol on the activities of 3-hydroxy-3-methylglutaryl-coenzyme A-reductase and squalene-hopene-cyclase in Zymomonas mobilis
Appl. Microbiol. Biotechnol.
30
170-175
1989
Zymomonas mobilis
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Siedenburg, G.; Jendrossek, D.
Squalene-hopene cyclases
Appl. Environ. Microbiol.
77
3905-3915
2011
Alicyclobacillus acidocaldarius, Alicyclobacillus acidocaldarius (P33247), Bradyrhizobium japonicum, Methylococcus capsulatus, Rhodopseudomonas palustris, Streptomyces peucetius, Tetrahymena thermophila, Zymomonas mobilis, no activity in Methylococcus capsulatus
Siedenburg, G.; Breuer, M.; Jendrossek, D.
Prokaryotic squalene-hopene cyclases can be converted to citronellal cyclases by single amino acid exchange
Appl. Microbiol. Biotechnol.
97
1571-1580
2013
Bradyrhizobium japonicum, Rhodopseudomonas palustris, Teredinibacter turnerae, Syntrophobacter fumaroxidans (A0LJS0), Alicyclobacillus acidocaldarius (P33247), Zymomonas mobilis (P33990), Zymomonas mobilis (Q5NM88), Burkholderia ambifaria (Q0B2H5), Burkholderia ambifaria (Q0B5S3), Bacillus anthracis (Q81YD8), Streptomyces coelicolor (Q9X7V9), Acetobacter pasteurianus (YP3187836), Burkholderia ambifaria ATCC BAA-244 / AMMD (Q0B2H5), Burkholderia ambifaria ATCC BAA-244 / AMMD (Q0B5S3), Zymomonas mobilis ATCC 31821 (P33990), Zymomonas mobilis CP4 (Q5NM88), Alicyclobacillus acidocaldarius DSM 446 (P33247)
Seitz, M.; Syren, P.; Steiner, L.; Klebensberger, J.; Nestl, B.; Hauer, B.
Synthesis of heterocyclic terpenoids by promiscuous squalene-hopene cyclases
ChemBioChem
14
436-439
2013
Alicyclobacillus acidocaldarius, Zymomonas mobilis
Seitz, M.; Klebensberger, J.; Siebenhaller, S.; Breuer, M.; Siedenburg, G.; Jendrossek, D.; Hauer, B.
Substrate specificity of a novel squalene-hopene cyclase from Zymomonas mobilis
J. Mol. Catal. B
84
72-77
2012
Zymomonas mobilis (Q5NM88), Zymomonas mobilis CP4 (Q5NM88)
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Hammer, S.; Dominicus, J.; Syrén, P.; Nestl, B.; Hauer, B.
Stereoselective Friedel-Crafts alkylation catalyzed by squalene hopene cyclases
Tetrahedron
68
7624-7629
2012
Zymomonas mobilis (Q5NM88), Zymomonas mobilis CP4 (Q5NM88)
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