ID   COMT3_POPKI             Reviewed;         364 AA.
AC   Q43047;
DT   11-APR-2003, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   03-AUG-2022, entry version 86.
DE   RecName: Full=Caffeic acid 3-O-methyltransferase 3;
DE            Short=CAOMT-3;
DE            Short=COMT-3;
DE            EC=2.1.1.68;
DE   AltName: Full=S-adenosysl-L-methionine:caffeic acid 3-O-methyltransferase 1;
GN   Name=HOMT3;
OS   Populus kitakamiensis (Aspen) (Populus sieboldii x Populus grandidentata).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   rosids; fabids; Malpighiales; Salicaceae; Saliceae; Populus.
OX   NCBI_TaxID=34292;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RA   Hayakawa T., Nanto K., Kawai S., Katayama Y., Morohoshi N.;
RT   "Molecular cloning and tissue-specific expression of two genes that encode
RT   caffeic acid O-methyltransferases from Populus kitakamiensis.";
RL   Plant Sci. 113:157-165(1996).
CC   -!- FUNCTION: Catalyzes the conversion of caffeic acid to ferulic acid and
CC       of 5-hydroxyferulic acid to sinapic acid. The resulting products may
CC       subsequently be converted to the corresponding alcohols that are
CC       incorporated into lignins.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=(E)-caffeate + S-adenosyl-L-methionine = (E)-ferulate + H(+) +
CC         S-adenosyl-L-homocysteine; Xref=Rhea:RHEA:20225, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:29749, ChEBI:CHEBI:57770, ChEBI:CHEBI:57856,
CC         ChEBI:CHEBI:59789; EC=2.1.1.68;
CC   -!- PATHWAY: Aromatic compound metabolism; phenylpropanoid biosynthesis.
CC   -!- SUBUNIT: Homodimer. {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the class I-like SAM-binding methyltransferase
CC       superfamily. Cation-independent O-methyltransferase family. COMT
CC       subfamily. {ECO:0000255|PROSITE-ProRule:PRU01020}.
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DR   EMBL; D49711; BAA08559.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q43047; -.
DR   SMR; Q43047; -.
DR   UniPathway; UPA00711; -.
DR   GO; GO:0047763; F:caffeate O-methyltransferase activity; IEA:UniProtKB-EC.
DR   GO; GO:0046983; F:protein dimerization activity; IEA:InterPro.
DR   GO; GO:0009809; P:lignin biosynthetic process; IEA:UniProtKB-KW.
DR   GO; GO:0032259; P:methylation; IEA:UniProtKB-KW.
DR   Gene3D; 1.10.10.10; -; 1.
DR   Gene3D; 3.40.50.150; -; 1.
DR   InterPro; IPR016461; COMT-like.
DR   InterPro; IPR001077; O_MeTrfase_dom.
DR   InterPro; IPR012967; Plant_MeTrfase_dimerisation.
DR   InterPro; IPR029063; SAM-dependent_MTases_sf.
DR   InterPro; IPR036388; WH-like_DNA-bd_sf.
DR   InterPro; IPR036390; WH_DNA-bd_sf.
DR   PANTHER; PTHR11746; PTHR11746; 1.
DR   Pfam; PF08100; Dimerisation; 1.
DR   Pfam; PF00891; Methyltransf_2; 1.
DR   PIRSF; PIRSF005739; O-mtase; 1.
DR   SUPFAM; SSF46785; SSF46785; 1.
DR   SUPFAM; SSF53335; SSF53335; 1.
DR   PROSITE; PS51683; SAM_OMT_II; 1.
PE   3: Inferred from homology;
KW   Lignin biosynthesis; Methyltransferase; S-adenosyl-L-methionine;
KW   Transferase.
FT   CHAIN           1..364
FT                   /note="Caffeic acid 3-O-methyltransferase 3"
FT                   /id="PRO_0000063208"
FT   REGION          161..179
FT                   /note="Substrate binding"
FT                   /evidence="ECO:0000250"
FT   ACT_SITE        268
FT                   /note="Proton acceptor"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
FT   BINDING         129..135
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250"
FT   BINDING         207
FT                   /ligand="S-adenosyl-L-methionine"
FT                   /ligand_id="ChEBI:CHEBI:59789"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
FT   BINDING         230
FT                   /ligand="S-adenosyl-L-methionine"
FT                   /ligand_id="ChEBI:CHEBI:59789"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
FT   BINDING         250
FT                   /ligand="S-adenosyl-L-methionine"
FT                   /ligand_id="ChEBI:CHEBI:59789"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
FT   BINDING         251
FT                   /ligand="S-adenosyl-L-methionine"
FT                   /ligand_id="ChEBI:CHEBI:59789"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
FT   BINDING         264
FT                   /ligand="S-adenosyl-L-methionine"
FT                   /ligand_id="ChEBI:CHEBI:59789"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01020"
SQ   SEQUENCE   364 AA;  39576 MW;  6322956A988EE6C1 CRC64;
     MGSTGETQMS PAQILDEEAN FAMQLISSSV LPMVLKTAIE LDLLEIMAKA GPGALLSPSD
     IASHLPTKNP DAPVMLDRIL RLLASYSILI CSLRDLPDGK VERLYGLASV CKFLTKNEDG
     VSVSPLCLMN QDKVLMESWY HLKDAILEGG IPFNKAYGMT AFEYHGTDPR FNKVFNKGMS
     DHSKMAMKKI LESYKGFEGL ASLVDVGGGT GAVVSTIVSK YPSIKGINFD LPHVIADAPA
     FPGVENVGGD MFVSVPKADA VFMKWICHDW SDEHCLRLLK NCYDALPENG KVILVECILP
     VAPDTSLATK GVMHVDAIML AHNPGGKERT DKEFEGLARG AGFKGFEVMC CAFNTHVIEF
     RKQA