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P28012 (CFI1_MEDSA) Reviewed, UniProtKB/Swiss-Prot

Last modified July 9, 2014. Version 75. Feed History...

Clusters with 100%, 90%, 50% identity | Documents (3) | Third-party data text xml rdf/xml gff fasta
to top of pageNames·Attributes·General annotation·Ontologies·Sequence annotation·Sequences·References·Cross-refs·Entry info·DocumentsCustomize order

Names and origin

Protein namesRecommended name:
Chalcone--flavonone isomerase 1

Short name=Chalcone isomerase 1
EC=5.5.1.6
Gene names
Name:CHI1
Synonyms:CHI-1
OrganismMedicago sativa (Alfalfa)
Taxonomic identifier3879 [NCBI]
Taxonomic lineageEukaryotaViridiplantaeStreptophytaEmbryophytaTracheophytaSpermatophytaMagnoliophytaeudicotyledonsGunneridaePentapetalaerosidsfabidsFabalesFabaceaePapilionoideaeTrifolieaeMedicago

Protein attributes

Sequence length222 AA.
Sequence statusComplete.
Protein existenceEvidence at protein level

General annotation (Comments)

Function

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. Ref.3 Ref.4 Ref.5

Catalytic activity

A chalcone = a flavanone.

Pathway

Secondary metabolite biosynthesis; flavonoid biosynthesis.

Developmental stage

Highest expression in young root tips.

Miscellaneous

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

Sequence similarities

Belongs to the chalcone isomerase family.

Biophysicochemical properties

Kinetic parameters:

KM=8.4 µM for 4,2',4'-trihydroxychalcone (at pH 7.5 and 25 degrees Celsius) Ref.3 Ref.4 Ref.5

KM=15.7 µM for 6'-deoxychalcone (at pH 7.5 and 25 degrees Celsius)

KM=22.7 µM for 2',4'-dihydroxychalcone (at pH 7.5 and 25 degrees Celsius)

KM=42.5 µM for 4,2'-dihydroxychalcone (at pH 7.5 and 25 degrees Celsius)

KM=112 µM for 4,2',4',6'-tetrahydroxychalcone (at pH 7.5 and 25 degrees Celsius)

pH dependence:

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

Ontologies

Keywords
   Biological processFlavonoid biosynthesis
   Molecular functionIsomerase
   Technical term3D-structure
Gene Ontology (GO)
   Biological_processflavonoid biosynthetic process

Inferred from electronic annotation. Source: UniProtKB-UniPathway

   Molecular_functionchalcone isomerase activity

Inferred from electronic annotation. Source: UniProtKB-EC

Complete GO annotation...

Sequence annotation (Features)

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifier

Molecule processing

Chain1 – 222222Chalcone--flavonone isomerase 1
PRO_0000166434

Sites

Binding site481Substrate By similarity
Binding site1131Substrate By similarity
Binding site1901Substrate By similarity
Site1061Important for catalytic activity

Experimental info

Mutagenesis481T → A: Strongly reduced reaction rate. Ref.4
Mutagenesis481T → S: Reduced reaction rate. Ref.4
Mutagenesis1061Y → F: Strongly reduced reaction rate. Ref.3 Ref.4
Mutagenesis1131N → A: Reduced reaction rate. Ref.4
Mutagenesis1901T → A: Reduced reaction rate. Ref.4

Secondary structure

...................................... 222
Helix Strand Turn

Details...

Sequences

Sequence LengthMass (Da)Tools
P28012 [UniParc].

Last modified August 1, 1992. Version 1.
Checksum: 7767A72084AB4800

FASTA22223,826
        10         20         30         40         50         60 
MAASITAITV ENLEYPAVVT SPVTGKSYFL GGAGERGLTI EGNFIKFTAI GVYLEDIAVA 

        70         80         90        100        110        120 
SLAAKWKGKS SEELLETLDF YRDIISGPFE KLIRGSKIRE LSGPEYSRKV MENCVAHLKS 

       130        140        150        160        170        180 
VGTYGDAEAE AMQKFAEAFK PVNFPPGASV FYRQSPDGIL GLSFSPDTSI PEKEAALIEN 

       190        200        210        220 
KAVSSAVLET MIGEHAVSPD LKRCLAARLP ALLNEGAFKI GN 

« Hide

References

[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.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ
M91079 mRNA. Translation: AAB41524.1.
PIRS44371.

3D structure databases

PDBe
RCSB-PDB
PDBj
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[»]
ProteinModelPortalP28012.
SMRP28012. Positions 4-215.
ModBaseSearch...
MobiDBSearch...

Proteomic databases

ProMEXP28012.

Protocols and materials databases

StructuralBiologyKnowledgebaseSearch...

Enzyme and pathway databases

BioCycMetaCyc:MONOMER-18291.
UniPathwayUPA00154.

Family and domain databases

Gene3D3.50.70.10. 1 hit.
InterProIPR016087. Chalcone_isomerase.
IPR016088. Chalcone_isomerase_3-sand.
[Graphical view]
PfamPF02431. Chalcone. 1 hit.
[Graphical view]
SUPFAMSSF54626. SSF54626. 1 hit.
ProtoNetSearch...

Other

EvolutionaryTraceP28012.

Entry information

Entry nameCFI1_MEDSA
AccessionPrimary (citable) accession number: P28012
Entry history
Integrated into UniProtKB/Swiss-Prot: August 1, 1992
Last sequence update: August 1, 1992
Last modified: July 9, 2014
This is version 75 of the entry and version 1 of the sequence. [Complete history]
Entry statusReviewed (UniProtKB/Swiss-Prot)
Annotation programPlant Protein Annotation Program

Relevant documents

SIMILARITY comments

Index of protein domains and families

PDB cross-references

Index of Protein Data Bank (PDB) cross-references

PATHWAY comments

Index of metabolic and biosynthesis pathways