ID   CFI_CITSI               Reviewed;         222 AA.
AC   Q9ZWR1;
DT   11-SEP-2007, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1999, sequence version 1.
DT   03-AUG-2022, entry version 79.
DE   RecName: Full=Chalcone--flavanone isomerase;
DE            Short=Chalcone isomerase;
DE            EC=5.5.1.6;
GN   Name=CHI;
OS   Citrus sinensis (Sweet orange) (Citrus aurantium var. sinensis).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   rosids; malvids; Sapindales; Rutaceae; Aurantioideae; Citrus.
OX   NCBI_TaxID=2711;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], TISSUE SPECIFICITY, AND DEVELOPMENTAL STAGE.
RC   STRAIN=cv. Valencia;
RX   DOI=10.1034/j.1399-3054.2001.1110109.x;
RA   Moriguchi T., Kita M., Tomono Y., Endo-Inagaki T., Omura M.;
RT   "Gene expression in flavonoid biosynthesis: correlation with flavonoid
RT   accumulation in developing citrus fruit.";
RL   Physiol. Plantarum 111:66-74(2001).
CC   -!- FUNCTION: Catalyzes the intramolecular cyclization of bicyclic
CC       chalcones into tricyclic (S)-flavanones. Responsible for the
CC       isomerization of 4,2',4',6'-tetrahydroxychalcone (also termed chalcone)
CC       into naringenin (By similarity). {ECO:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=a chalcone = a flavanone.; EC=5.5.1.6;
CC   -!- PATHWAY: Secondary metabolite biosynthesis; flavonoid biosynthesis.
CC   -!- TISSUE SPECIFICITY: Expressed in leaves, flowers and fruits.
CC       {ECO:0000269|Ref.1}.
CC   -!- DEVELOPMENTAL STAGE: Accumulates in young fruitlets but disappears
CC       progressively one month after fecondation. {ECO:0000269|Ref.1}.
CC   -!- MISCELLANEOUS: Part of the biosynthetic pathway for all classes of
CC       flavonoids, a large class of secondary plant metabolites, many of which
CC       are brightly colored.
CC   -!- SIMILARITY: Belongs to the chalcone isomerase family. {ECO:0000305}.
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DR   EMBL; AB011794; BAA36552.1; -; mRNA.
DR   RefSeq; NP_001275866.1; NM_001288937.1.
DR   AlphaFoldDB; Q9ZWR1; -.
DR   SMR; Q9ZWR1; -.
DR   STRING; 2711.XP_006485998.1; -.
DR   GeneID; 102615441; -.
DR   KEGG; cit:102615441; -.
DR   eggNOG; ENOG502QR5P; Eukaryota.
DR   OrthoDB; 1158490at2759; -.
DR   UniPathway; UPA00154; -.
DR   GO; GO:0045430; F:chalcone isomerase activity; IEA:UniProtKB-EC.
DR   GO; GO:0009813; P:flavonoid biosynthetic process; IEA:UniProtKB-UniPathway.
DR   Gene3D; 1.10.890.20; -; 1.
DR   Gene3D; 3.50.70.10; -; 1.
DR   InterPro; IPR044164; CFI.
DR   InterPro; IPR016087; Chalcone_isomerase.
DR   InterPro; IPR016088; Chalcone_isomerase_3-sand.
DR   InterPro; IPR016089; Chalcone_isomerase_bundle_sf.
DR   InterPro; IPR036298; Chalcone_isomerase_sf.
DR   PANTHER; PTHR28039; PTHR28039; 1.
DR   Pfam; PF02431; Chalcone; 1.
DR   SUPFAM; SSF54626; SSF54626; 1.
PE   2: Evidence at transcript level;
KW   Flavonoid biosynthesis; Isomerase.
FT   CHAIN           1..222
FT                   /note="Chalcone--flavanone isomerase"
FT                   /id="PRO_0000300833"
FT   BINDING         50
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         115
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         191
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   SITE            108
FT                   /note="Important for catalytic activity"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   222 AA;  23981 MW;  4140B76F2FCC3306 CRC64;
     MNPSPSVTEL QVENVTFTPS VQPPGSTKSH FLGGAGERGL EIEGKFVKFT AIGVYLEDDA
     VPLLAGKWKG KTAEELTESV EFFRDVVTGP FEKFMKVTMI LPLTGAQYSE KVAENCIAIW
     KFFGIYTDAE AKAIEKFTEV FKDEIFPPGS SILFTQSPGS LTISFSKDGS IPKDGVAVIE
     SNLLSEAVLE SMIGKNGVSP AAKKSLAERL SALLNVTSDK MK