ID   ATNI_ARTSZ              Reviewed;         707 AA.
AC   A0A455LN86;
DT   02-JUN-2021, integrated into UniProtKB/Swiss-Prot.
DT   05-JUN-2019, sequence version 1.
DT   25-MAY-2022, entry version 13.
DE   RecName: Full=Terpene cyclase/mutase atnI {ECO:0000303|PubMed:29797385};
DE            EC=5.4.99.- {ECO:0000305|PubMed:29797385};
DE   AltName: Full=Arthripenoid biosynthesis cluster protein I {ECO:0000303|PubMed:29797385};
GN   Name=atnI {ECO:0000303|PubMed:29797385};
OS   Arthrinium sp.
OC   Eukaryota; Fungi; Dikarya; Ascomycota; Pezizomycotina; Sordariomycetes;
OC   Xylariomycetidae; Xylariales; Apiosporaceae; Arthrinium;
OC   unclassified Arthrinium.
OX   NCBI_TaxID=1756131;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], DISRUPTION PHENOTYPE, FUNCTION, AND PATHWAY.
RC   STRAIN=NF2194;
RX   PubMed=29797385; DOI=10.1002/anie.201804317;
RA   Zhang X., Wang T.T., Xu Q.L., Xiong Y., Zhang L., Han H., Xu K., Guo W.J.,
RA   Xu Q., Tan R.X., Ge H.M.;
RT   "Genome mining and comparative biosynthesis of meroterpenoids from two
RT   phylogenetically distinct fungi.";
RL   Angew. Chem. Int. Ed. 57:8184-8188(2018).
CC   -!- FUNCTION: Terpene cyclase/mutase; part of the gene cluster that
CC       mediates the biosynthesis of the meroterpenoids arthripenoids
CC       (PubMed:29797385). The pathway begins with the HR-PKS atnH that
CC       catalyzes two chain-extension steps to form a reduced triketide, which
CC       then primes the SAT domain in the NR-PKS atnG to initiate three more
CC       cycles of extension to give a linear hexaketide corresponding to the
CC       polyketide part of arthripenoids (PubMed:29797385). The FAD-dependent
CC       monooxygenase atnJ then performs an oxidative decarboxylation at C11 of
CC       the atnH/atnG product, via an electrophilic aromatic hydroxylation with
CC       concomitant ipso-decarboxylation (PubMed:29797385). The membrane-bound
CC       polyprenyl transferase atnF then introduces a farnesyl group before the
CC       FAD-dependent monooxygenase atnK functions as the first epoxidase on
CC       terminal C12'-C13' olefin, followed by a second epoxidation on C7'-C8'
CC       catalyzed by atnA (PubMed:29797385). The terpene cyclase/mutase atnI
CC       then initiates the sequential tricyclic ring formation through
CC       protonation of the terminal epoxide and catalyzes the regioselective
CC       and stereoselective 6/6/6-tricyclic ring formation (PubMed:29797385).
CC       The cytochrome P450 monooxygenase atnM is responsible for hydroxylating
CC       both C1' and C10' (Probable). The next steps may involve ketoreduction
CC       and acetyl transfer by the ketoreductase atnB and the acetyltransferase
CC       atnC, and lead to the production of arthripenoid B, the final
CC       biosynthetic product of the atn cluster (PubMed:29797385). The
CC       hydroquinone moiety in arthripenoid B is prone to undergo spontaneous
CC       oxidation to afford a benzoquinone compound, a key intermediate for
CC       generating structure diversity (Probable). For instance, addition of a
CC       cysteine followed by ring contraction gives arthripenoid A,
CC       tautomerization gives the main product arthripenoid C, addition of a
CC       molecular of water or amine affords arthripenoid D or E, respectively,
CC       and loss of one water forms arthripenoid F (Probable).
CC       {ECO:0000269|PubMed:29797385, ECO:0000305|PubMed:29797385}.
CC   -!- PATHWAY: Secondary metabolite biosynthesis; terpenoid biosynthesis.
CC       {ECO:0000269|PubMed:29797385}.
CC   -!- DISRUPTION PHENOTYPE: Abolishes the production of arthripenoids but
CC       leads to the accumulation of a new compound that possesses a
CC       sesquiterpenoid chain with adiol group at C12' and C13' position.
CC       {ECO:0000269|PubMed:29797385}.
CC   -!- SIMILARITY: Belongs to the terpene cyclase/mutase family.
CC       {ECO:0000305}.
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DR   EMBL; MH183015; AYO60882.1; -; mRNA.
DR   AlphaFoldDB; A0A455LN86; -.
DR   SMR; A0A455LN86; -.
DR   UniPathway; UPA00213; -.
DR   GO; GO:0005811; C:lipid droplet; IEA:InterPro.
DR   GO; GO:0016866; F:intramolecular transferase activity; IEA:InterPro.
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; 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.
PE   2: Evidence at transcript level;
KW   Isomerase; Repeat.
FT   CHAIN           1..707
FT                   /note="Terpene cyclase/mutase atnI"
FT                   /id="PRO_0000452568"
FT   REPEAT          130..173
FT                   /note="PFTB 1"
FT                   /evidence="ECO:0000255"
FT   REPEAT          494..535
FT                   /note="PFTB 2"
FT                   /evidence="ECO:0000255"
FT   REPEAT          571..608
FT                   /note="PFTB 3"
FT                   /evidence="ECO:0000255"
FT   REPEAT          620..661
FT                   /note="PFTB 4"
FT                   /evidence="ECO:0000255"
FT   REGION          1..22
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        1..19
FT                   /note="Polar residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   SITE            397
FT                   /note="Transition state stabilizer"
FT                   /evidence="ECO:0000250|UniProtKB:P48449"
FT   SITE            454
FT                   /note="Transition state stabilizer"
FT                   /evidence="ECO:0000250|UniProtKB:P48449"
FT   SITE            592
FT                   /note="Transition state stabilizer"
FT                   /evidence="ECO:0000250|UniProtKB:P48449"
SQ   SEQUENCE   707 AA;  79228 MW;  C65109E1D91CD4F9 CRC64;
     MGQHIASSES STNGHVSLET NGDEKTDYSR WRLIDDQGRQ SWRYLESDKE RVDWPQTTYE
     KHFLGLDTEL PDLTKAQTPL QAAQGAMSYF SQLQLPSGQW ASECIGPLFI LAFVVIAGYV
     TDTPLPAGYA VEIRRYLFAR QCVADGGWGW HAEASESSAI GTVLSYVVLR LLGTTRDDPR
     LVRARTLLHE FGGATHAPGL AKFWLCILGV MKWECVNPFL PEFWLSPDSD PASPSKWYLH
     TRTNFTSMSY VWSKQWSYAG DAITEQLKAE LYTQPYDTID FAGHRSSLAA VDNNYPKWWL
     VNLMNWLTVA VYIPYFRKPA TAESAERKVW DLIVTEDKNT EYIGLSPISK AANLVACYIH
     DGPDGSSVRA HRRTMGQYFW MTQDGMACNL SDGIQVWDTS LAVQALCAAG ASSNPRFQST
     LVKAHAFLAD HQLLEDVQDQ EKCHRWPRKG GWPFSTRYQG YMISECTGEG LRSAMQLQGI
     SHLGLTQRIP EERLRDAVEC LLNLQNDTGG FGVYEKRLGS PKLAWLEMGE FVGKTMVTYD
     YVECTTAAVS ALLSFSKLHP NYRAAEIEAT TAQGLGFIKQ SQKPDGGWYG AWGVCFTYAG
     MFALETLALA GETYATSEAS RRGCDFLLDK QKDDGGWGES YLSLQREEYV QHEESQVVQT
     AWVCMALMHA GYPGREPIKR GLRLIMSRQQ SKGQWYQEAL EGGVGDG