ID   CUCS_CUCPE              Reviewed;         764 AA.
AC   Q6BE24;
DT   19-OCT-2011, integrated into UniProtKB/Swiss-Prot.
DT   13-SEP-2004, sequence version 1.
DT   03-AUG-2022, entry version 55.
DE   RecName: Full=Cucurbitadienol synthase;
DE            EC=5.4.99.33;
GN   Name=CPQ;
OS   Cucurbita pepo (Vegetable marrow) (Summer squash).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   rosids; fabids; Cucurbitales; Cucurbitaceae; Cucurbiteae; Cucurbita.
OX   NCBI_TaxID=3663;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, CATALYTIC ACTIVITY, AND MUTAGENESIS
RP   OF 488-LEU-ILE-489.
RX   DOI=10.1016/j.tet.2004.04.088;
RA   Shibuya M., Adachi S., Ebizuka Y.;
RT   "Cucurbitadienol synthase, the first committed enzyme for cucurbitacin
RT   biosynthesis, is a distinct enzyme from cycloartenol synthase for
RT   phytosterol biosynthesis.";
RL   Tetrahedron 60:6995-7003(2004).
CC   -!- FUNCTION: Oxidosqualene cyclase involved in the biosynthesis of the
CC       highly oxygenated tetracyclic triterpenes cucurbitacins. Converts
CC       oxidosqualene to cucurbitadienol and does not produce lanosterol.
CC       {ECO:0000269|Ref.1}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=(S)-2,3-epoxysqualene = cucurbitadienol; Xref=Rhea:RHEA:30999,
CC         ChEBI:CHEBI:15441, ChEBI:CHEBI:62456; EC=5.4.99.33;
CC         Evidence={ECO:0000269|Ref.1};
CC   -!- SIMILARITY: Belongs to the terpene cyclase/mutase family.
CC       {ECO:0000305}.
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DR   EMBL; AB116238; BAD34645.1; -; mRNA.
DR   AlphaFoldDB; Q6BE24; -.
DR   SMR; Q6BE24; -.
DR   KEGG; ag:BAD34645; -.
DR   BioCyc; MetaCyc:MON-16525; -.
DR   BRENDA; 5.4.99.33; 1740.
DR   GO; GO:0005811; C:lipid droplet; IEA:InterPro.
DR   GO; GO:0034076; F:cucurbitadienol synthase activity; IDA:UniProtKB.
DR   GO; GO:0016104; P:triterpenoid biosynthetic process; IEA:InterPro.
DR   CDD; cd02892; SQCY_1; 1.
DR   InterPro; IPR032696; SQ_cyclase_C.
DR   InterPro; IPR032697; SQ_cyclase_N.
DR   InterPro; IPR018333; Squalene_cyclase.
DR   InterPro; IPR002365; Terpene_synthase_CS.
DR   InterPro; IPR008930; Terpenoid_cyclase/PrenylTrfase.
DR   PANTHER; PTHR11764; PTHR11764; 1.
DR   Pfam; PF13243; SQHop_cyclase_C; 1.
DR   Pfam; PF13249; SQHop_cyclase_N; 1.
DR   SUPFAM; SSF48239; SSF48239; 2.
DR   TIGRFAMs; TIGR01787; squalene_cyclas; 1.
DR   PROSITE; PS01074; TERPENE_SYNTHASES; 1.
PE   1: Evidence at protein level;
KW   Isomerase; Repeat.
FT   CHAIN           1..764
FT                   /note="Cucurbitadienol synthase"
FT                   /id="PRO_0000412984"
FT   REPEAT          104..146
FT                   /note="PFTB 1"
FT   REPEAT          154..195
FT                   /note="PFTB 2"
FT   REPEAT          520..565
FT                   /note="PFTB 3"
FT   REPEAT          597..637
FT                   /note="PFTB 4"
FT   REPEAT          646..687
FT                   /note="PFTB 5"
FT   ACT_SITE        491
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000250|UniProtKB:P48449"
FT   MUTAGEN         488
FT                   /note="L->P: No change of product-specificity. No change of
FT                   product-specificity; when associated with V-489."
FT   MUTAGEN         489
FT                   /note="I->V: No change of product-specificity. No change of
FT                   product-specificity; when associated with P-488."
SQ   SEQUENCE   764 AA;  86517 MW;  27C59E3B5A6BEC05 CRC64;
     MWRLKVGAES VGEEDEKWVK SVSNHLGRQV WEFCADAAAD TPHQLLQIQN ARNHFHHNRF
     HRKQSSDLFL AIQYEKEIAK GAKGGAVKVK EGEEVGKEAV KSTLERALGF YSAVQTRDGN
     WASDLGGPLF LLPGLVIALH VTGVLNSVLS KHHRVEMCRY LYNHQNEDGG WGLHIEGTST
     MFGSALNYVA LRLLGEDADG GDGGAMTKAR AWILERGGAT AITSWGKLWL SVLGVYEWSG
     NNPLPPEFWL LPYSLPFHPG RMWCHCRMVY LPMSYLYGKR FVGPITPKVL SLRQELYTIP
     YHEIDWNKSR NTCAKEDLYY PHPKMQDILW GSIYHVYEPL FTRWPGKRLR EKALQAAMKH
     IHYEDENSRY ICLGPVNKVL NMLCCWVEDP YSDAFKLHLQ RVHDYLWVAE DGMRMQGYNG
     SQLWDTAFSI QAIVATKLVD SYAPTLRKAH DFVKDSQIQE DCPGDPNVWF RHIHKGAWPL
     STRDHGWLIS DCTAEGLKAS LMLSKLPSTM VGEPLEKNRL CDAVNVLLSL QNDNGGFASY
     ELTRSYPWLE LINPAETFGD IVIDYPYVEC TAATMEALTL FKKLHPGHRT KEIDTAIGKA
     ANFLEKMQRA DGSWYGCWGV CFTYAGWFGI KGLVAAGRTY NSCLAIRKAC EFLLSKELPG
     GGWGESYLSC QNKVYTNLEG NKPHLVNTAW VLMALIEAGQ GERDPAPLHR AARLLMNSQL
     ENGDFVQQEI MGVFNKNCMI TYAAYRNIFP IWALGEYCHR VLTE