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Protein

Chalcone--flavonone isomerase 1

Gene

CHI1

Organism
Medicago sativa (Alfalfa)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Catalyzes the intramolecular cyclization of bicyclic chalcones into tricyclic (S)-flavanones. Responsible for the isomerization of 4,2',4',6'-tetrahydroxychalcone (also termed chalcone) into naringenin.3 Publications

Catalytic activityi

A chalcone = a flavanone.

Kineticsi

  1. KM=8.4 µM for 4,2',4'-trihydroxychalcone (at pH 7.5 and 25 degrees Celsius)3 Publications
  2. KM=15.7 µM for 6'-deoxychalcone (at pH 7.5 and 25 degrees Celsius)3 Publications
  3. KM=22.7 µM for 2',4'-dihydroxychalcone (at pH 7.5 and 25 degrees Celsius)3 Publications
  4. KM=42.5 µM for 4,2'-dihydroxychalcone (at pH 7.5 and 25 degrees Celsius)3 Publications
  5. KM=112 µM for 4,2',4',6'-tetrahydroxychalcone (at pH 7.5 and 25 degrees Celsius)3 Publications

    pH dependencei

    Optimum pH is 7-8.5 with 4,2',4'-trihydroxychalcone as substrate, at 25 degrees Celsius.3 Publications

    Pathway: flavonoid biosynthesis

    This protein is involved in the pathway flavonoid biosynthesis, which is part of Secondary metabolite biosynthesis.
    View all proteins of this organism that are known to be involved in the pathway flavonoid biosynthesis and in Secondary metabolite biosynthesis.

    Sites

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Binding sitei48 – 481SubstrateBy similarity
    Sitei106 – 1061Important for catalytic activity
    Binding sitei113 – 1131SubstrateBy similarity
    Binding sitei190 – 1901SubstrateBy similarity

    GO - Molecular functioni

    GO - Biological processi

    Complete GO annotation...

    Keywords - Molecular functioni

    Isomerase

    Keywords - Biological processi

    Flavonoid biosynthesis

    Enzyme and pathway databases

    BioCyciMetaCyc:MONOMER-18291.
    BRENDAi5.5.1.6. 3078.
    SABIO-RKP28012.
    UniPathwayiUPA00154.

    Names & Taxonomyi

    Protein namesi
    Recommended name:
    Chalcone--flavonone isomerase 1 (EC:5.5.1.6)
    Short name:
    Chalcone isomerase 1
    Gene namesi
    Name:CHI1
    Synonyms:CHI-1
    OrganismiMedicago sativa (Alfalfa)
    Taxonomic identifieri3879 [NCBI]
    Taxonomic lineageiEukaryotaViridiplantaeStreptophytaEmbryophytaTracheophytaSpermatophytaMagnoliophytaeudicotyledonsGunneridaePentapetalaerosidsfabidsFabalesFabaceaePapilionoideaeTrifolieaeMedicago

    Pathology & Biotechi

    Mutagenesis

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Mutagenesisi48 – 481T → A: Strongly reduced reaction rate. 1 Publication
    Mutagenesisi48 – 481T → S: Reduced reaction rate. 1 Publication
    Mutagenesisi106 – 1061Y → F: Strongly reduced reaction rate. 2 Publications
    Mutagenesisi113 – 1131N → A: Reduced reaction rate. 1 Publication
    Mutagenesisi190 – 1901T → A: Reduced reaction rate. 1 Publication

    PTM / Processingi

    Molecule processing

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Chaini1 – 222222Chalcone--flavonone isomerase 1PRO_0000166434Add
    BLAST

    Expressioni

    Developmental stagei

    Highest expression in young root tips.

    Structurei

    Secondary structure

    1
    222
    Legend: HelixTurnBeta strand
    Show more details
    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Beta strandi8 – 103Combined sources
    Beta strandi13 – 153Combined sources
    Beta strandi17 – 204Combined sources
    Turni22 – 243Combined sources
    Beta strandi27 – 4014Combined sources
    Beta strandi43 – 5513Combined sources
    Helixi58 – 669Combined sources
    Helixi71 – 755Combined sources
    Helixi78 – 869Combined sources
    Beta strandi87 – 893Combined sources
    Beta strandi91 – 999Combined sources
    Helixi103 – 12018Combined sources
    Helixi126 – 13914Combined sources
    Beta strandi142 – 1443Combined sources
    Beta strandi149 – 1557Combined sources
    Turni156 – 1583Combined sources
    Beta strandi159 – 16911Combined sources
    Beta strandi175 – 1795Combined sources
    Helixi181 – 19212Combined sources
    Helixi200 – 21415Combined sources

    3D structure databases

    Select the link destinations:
    PDBei
    RCSB PDBi
    PDBji
    Links Updated
    EntryMethodResolution (Å)ChainPositionsPDBsum
    1EYPX-ray2.50A/B1-222[»]
    1EYQX-ray1.85A/B1-222[»]
    1FM7X-ray2.30A/B1-222[»]
    1FM8X-ray2.30A/B1-222[»]
    1JEPX-ray2.10A/B1-222[»]
    1JX0X-ray2.85A/B1-222[»]
    1JX1X-ray2.30A/B/C/D/E/F1-222[»]
    ProteinModelPortaliP28012.
    SMRiP28012. Positions 4-215.
    ModBaseiSearch...
    MobiDBiSearch...

    Miscellaneous databases

    EvolutionaryTraceiP28012.

    Family & Domainsi

    Sequence similaritiesi

    Belongs to the chalcone isomerase family.Curated

    Family and domain databases

    Gene3Di3.50.70.10. 1 hit.
    InterProiIPR016087. Chalcone_isomerase.
    IPR016088. Chalcone_isomerase_3-sand.
    [Graphical view]
    PfamiPF02431. Chalcone. 1 hit.
    [Graphical view]
    SUPFAMiSSF54626. SSF54626. 1 hit.

    Sequencei

    Sequence statusi: Complete.

    P28012-1 [UniParc]FASTAAdd to basket

    « Hide

            10         20         30         40         50
    MAASITAITV ENLEYPAVVT SPVTGKSYFL GGAGERGLTI EGNFIKFTAI
    60 70 80 90 100
    GVYLEDIAVA SLAAKWKGKS SEELLETLDF YRDIISGPFE KLIRGSKIRE
    110 120 130 140 150
    LSGPEYSRKV MENCVAHLKS VGTYGDAEAE AMQKFAEAFK PVNFPPGASV
    160 170 180 190 200
    FYRQSPDGIL GLSFSPDTSI PEKEAALIEN KAVSSAVLET MIGEHAVSPD
    210 220
    LKRCLAARLP ALLNEGAFKI GN
    Length:222
    Mass (Da):23,826
    Last modified:August 1, 1992 - v1
    Checksum:i7767A72084AB4800
    GO

    Sequence databases

    Select the link destinations:
    EMBLi
    GenBanki
    DDBJi
    Links Updated
    M91079 mRNA. Translation: AAB41524.1.
    PIRiS44371.

    Cross-referencesi

    Sequence databases

    Select the link destinations:
    EMBLi
    GenBanki
    DDBJi
    Links Updated
    M91079 mRNA. Translation: AAB41524.1.
    PIRiS44371.

    3D structure databases

    Select the link destinations:
    PDBei
    RCSB PDBi
    PDBji
    Links Updated
    EntryMethodResolution (Å)ChainPositionsPDBsum
    1EYPX-ray2.50A/B1-222[»]
    1EYQX-ray1.85A/B1-222[»]
    1FM7X-ray2.30A/B1-222[»]
    1FM8X-ray2.30A/B1-222[»]
    1JEPX-ray2.10A/B1-222[»]
    1JX0X-ray2.85A/B1-222[»]
    1JX1X-ray2.30A/B/C/D/E/F1-222[»]
    ProteinModelPortaliP28012.
    SMRiP28012. Positions 4-215.
    ModBaseiSearch...
    MobiDBiSearch...

    Protocols and materials databases

    Structural Biology KnowledgebaseSearch...

    Enzyme and pathway databases

    UniPathwayiUPA00154.
    BioCyciMetaCyc:MONOMER-18291.
    BRENDAi5.5.1.6. 3078.
    SABIO-RKP28012.

    Miscellaneous databases

    EvolutionaryTraceiP28012.

    Family and domain databases

    Gene3Di3.50.70.10. 1 hit.
    InterProiIPR016087. Chalcone_isomerase.
    IPR016088. Chalcone_isomerase_3-sand.
    [Graphical view]
    PfamiPF02431. Chalcone. 1 hit.
    [Graphical view]
    SUPFAMiSSF54626. SSF54626. 1 hit.
    ProtoNetiSearch...

    Publicationsi

    1. "Isolation of chalcone synthase and chalcone isomerase cDNAs from alfalfa (Medicago sativa L.): highest transcript levels occur in young roots and root tips."
      McKhann H.I., Hirsch A.M.
      Plant Mol. Biol. 24:767-777(1994) [PubMed] [Europe PMC] [Abstract]
      Cited for: NUCLEOTIDE SEQUENCE [MRNA].
      Strain: cv. Iroquois.
    2. Erratum
      McKhann H.I., Hirsch A.M.
      Plant Mol. Biol. 25:759-759(1994)
    3. "Structure and mechanism of the evolutionarily unique plant enzyme chalcone isomerase."
      Jez J.M., Bowman M.E., Dixon R.A., Noel J.P.
      Nat. Struct. Biol. 7:786-791(2000) [PubMed] [Europe PMC] [Abstract]
      Cited for: X-RAY CRYSTALLOGRAPHY (1.85 ANGSTROMS) IN COMPLEX WITH (2S)-NARINGENIN, FUNCTION, BIOPHYSICOCHEMICAL PROPERTIES, MUTAGENESIS OF TYR-106.
    4. "Role of hydrogen bonds in the reaction mechanism of chalcone isomerase."
      Jez J.M., Bowman M.E., Noel J.P.
      Biochemistry 41:5168-5176(2002) [PubMed] [Europe PMC] [Abstract]
      Cited for: X-RAY CRYSTALLOGRAPHY (2.3 ANGSTROMS), FUNCTION, BIOPHYSICOCHEMICAL PROPERTIES, MUTAGENESIS OF THR-48; TYR-106; ASN-113 AND THR-190.
    5. "Reaction mechanism of chalcone isomerase. pH dependence, diffusion control, and product binding differences."
      Jez J.M., Noel J.P.
      J. Biol. Chem. 277:1361-1369(2002) [PubMed] [Europe PMC] [Abstract]
      Cited for: X-RAY CRYSTALLOGRAPHY (2.1 ANGSTROMS), FUNCTION, BIOPHYSICOCHEMICAL PROPERTIES.

    Entry informationi

    Entry nameiCFI1_MEDSA
    AccessioniPrimary (citable) accession number: P28012
    Entry historyi
    Integrated into UniProtKB/Swiss-Prot: August 1, 1992
    Last sequence update: August 1, 1992
    Last modified: May 27, 2015
    This is version 80 of the entry and version 1 of the sequence. [Complete history]
    Entry statusiReviewed (UniProtKB/Swiss-Prot)
    Annotation programPlant Protein Annotation Program

    Miscellaneousi

    Miscellaneous

    Part of the biosynthetic pathway for all classes of flavonoids, a large class of secondary plant metabolites, many of which are brightly colored.

    Keywords - Technical termi

    3D-structure

    Documents

    1. PATHWAY comments
      Index of metabolic and biosynthesis pathways
    2. PDB cross-references
      Index of Protein Data Bank (PDB) cross-references
    3. SIMILARITY comments
      Index of protein domains and families

    External Data

    Dasty 3

    Similar proteinsi

    Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
    100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into Uniref entry.
    90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
    50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.