ID   CTB6_CERBT              Reviewed;         357 AA.
AC   A0A2G5ICG8;
DT   17-JUN-2020, integrated into UniProtKB/Swiss-Prot.
DT   31-JAN-2018, sequence version 1.
DT   03-AUG-2022, entry version 13.
DE   RecName: Full=Ketoreductase CTB6 {ECO:0000303|PubMed:29844193};
DE            EC=1.-.-.- {ECO:0000250|UniProtKB:A0ST44};
DE   AltName: Full=Cercosporin toxin biosynthesis cluster protein 6 {ECO:0000303|PubMed:29844193};
GN   Name=CTB6 {ECO:0000303|PubMed:29844193}; ORFNames=CB0940_00830;
OS   Cercospora beticola (Sugarbeet leaf spot fungus).
OC   Eukaryota; Fungi; Dikarya; Ascomycota; Pezizomycotina; Dothideomycetes;
OC   Dothideomycetidae; Mycosphaerellales; Mycosphaerellaceae; Cercospora.
OX   NCBI_TaxID=122368;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA], FUNCTION, AND PATHWAY.
RC   STRAIN=09-40;
RX   PubMed=29844193; DOI=10.1073/pnas.1712798115;
RA   de Jonge R., Ebert M.K., Huitt-Roehl C.R., Pal P., Suttle J.C.,
RA   Spanner R.E., Neubauer J.D., Jurick W.M. II, Stott K.A., Secor G.A.,
RA   Thomma B.P.H.J., Van de Peer Y., Townsend C.A., Bolton M.D.;
RT   "Gene cluster conservation provides insight into cercosporin biosynthesis
RT   and extends production to the genus Colletotrichum.";
RL   Proc. Natl. Acad. Sci. U.S.A. 115:E5459-E5466(2018).
RN   [2]
RP   REVIEW ON CERCOSPORIN.
RX   PubMed=11701851; DOI=10.1146/annurev.phyto.38.1.461;
RA   Daub M.E., Ehrenshaft M.;
RT   "The photoactivated cercospora toxin cercosporin: contributions to plant
RT   disease and fundamental biology.";
RL   Annu. Rev. Phytopathol. 38:461-490(2000).
CC   -!- FUNCTION: Ketoreductase; part of the gene cluster that mediates the
CC       biosynthesis of cercosporin, a light-activated, non-host-selective
CC       toxin (By similarity). The perylenequinone chromophore of cercosporin
CC       absorbs light energy to attain an electronically-activated triplet
CC       state and produces active oxygen species such as the hydroxyl radical,
CC       superoxide, hydrogen peroxide or singlet oxygen upon reaction with
CC       oxygen molecules (PubMed:11701851). These reactive oxygen species cause
CC       damage to various cellular components including lipids, proteins and
CC       nucleic acids (PubMed:11701851). The first step of cercosporin
CC       biosynthesis is performed by the polyketide synthase CTB1 which
CC       catalyzes the formation of nor-toralactone (By similarity). The starter
CC       unit acyltransferase (SAT) domain of CTB1 initiates polyketide
CC       extension by the selective utilization of acetyl-CoA, which is
CC       elongated to the heptaketide in the beta-ketoacyl synthase (KS) domain
CC       by successive condensations with six malonyl units introduced by the
CC       malonyl acyltransferase (MAT) domain. The product template (PT) domain
CC       catalyzes C4-C9 and C2-C11 aldol cyclizations and dehydrations to a
CC       trihydroxynaphthalene, which is thought to be delivered to the
CC       thioesterase (TE) domain for product release (By similarity). The
CC       bifunctional enzyme CTB3 then methylates nor-toralactone to toralactone
CC       before conducting an unusual oxidative aromatic ring opening (By
CC       similarity). The O-methyltransferase CTB2 further methylates the
CC       nascent OH-6 of the CBT3 product, blocking further oxidation at this
CC       site before the reductase CTB6 reduces the 2-oxopropyl ketone at
CC       position C7, giving naphthalene (By similarity). The FAD-dependent
CC       monooxygenase CTB5 in concert with the multicopper oxidase CTB12 are
CC       responsible for homodimerization of naphthalene with CTB7 installing
CC       the dioxepine moiety, finally producing cercosporin (By similarity).
CC       The fasciclin domain-containing protein CTB11 might act with CTB5 and
CC       CTB12 whereas the roles of CTB9 and CTB10 have still to be elucidated
CC       (By similarity). {ECO:0000250|UniProtKB:A0ST44,
CC       ECO:0000250|UniProtKB:Q0UHZ9, ECO:0000303|PubMed:11701851}.
CC   -!- PATHWAY: Mycotoxin biosynthesis. {ECO:0000250|UniProtKB:A0ST44}.
CC   -!- SIMILARITY: Belongs to the NAD(P)-dependent epimerase/dehydratase
CC       family. Dihydroflavonol-4-reductase subfamily. {ECO:0000305}.
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DR   EMBL; LKMD01000100; PIB02402.1; -; Genomic_DNA.
DR   AlphaFoldDB; A0A2G5ICG8; -.
DR   SMR; A0A2G5ICG8; -.
DR   OrthoDB; 992332at2759; -.
DR   Proteomes; UP000230605; Chromosome 1.
DR   GO; GO:0016491; F:oxidoreductase activity; IEA:UniProtKB-KW.
DR   InterPro; IPR001509; Epimerase_deHydtase.
DR   InterPro; IPR036291; NAD(P)-bd_dom_sf.
DR   Pfam; PF01370; Epimerase; 1.
DR   SUPFAM; SSF51735; SSF51735; 1.
PE   3: Inferred from homology;
KW   NADP; Oxidoreductase.
FT   CHAIN           1..357
FT                   /note="Ketoreductase CTB6"
FT                   /id="PRO_0000449875"
FT   BINDING         172
FT                   /ligand="NADP(+)"
FT                   /ligand_id="ChEBI:CHEBI:58349"
FT                   /evidence="ECO:0000250|UniProtKB:A0A059TC02"
SQ   SEQUENCE   357 AA;  39532 MW;  E1FB458D98D1B350 CRC64;
     MADSLVLLTG ATGFIGFRIL IELLRQGYSV RAVIRSAGKG QWLESRLTAV MKGSDYKDRF
     ETTTVADFVT DGAFDQAAEN TSYIIHVASP IVSSDNPDDW EHDFKRVAVK GSIGVLEAAK
     RSGTVRRVVI TSSMVGLFSP KALFAEPSEV PLNAESRIPE MEPPYAHKML AYQAGKIASI
     NSAEAWIKNE KPAFDLVHMH PSFVTGRDDL ATTREDLRKF SSNWHSMQIV LGHKNPIGKP
     ILTCHNDDVA RCHVLALDPK VTGNQSFLIS CSPEDGSEWD DVKKFVQREF PEAVAQGVLP
     NDGHMPTVNK GVRFDVRKTE ETFGFKHIPY EAQVLDVVKQ YLELPEKDEG VEISTTA