Reviewed, UniProtKB/Swiss-Prot P28002 (COMT1_MEDSA)

Names and origin

Protein names	Recommended name:     Caffeic acid 3-O-methyltransferase     EC=2.1.1.68 Alternative name(s):     S-adenosysl-L-methionine:caffeic acid 3-O-methyltransferase       Short name=CAOMT       Short name=COMT
Organism	Medicago sativa (Alfalfa)
Taxonomic identifier	3879 [NCBI]
Taxonomic lineage	Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › rosids › eurosids I › Fabales › Fabaceae › Papilionoideae › Trifolieae › Medicago

Protein attributes

Sequence length	365 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Catalyzes the conversion of caffeic acid to ferulic acid and of 5-hydroxyferulic acid to sinapic acid. The resulting products may subsequently be converted to the corresponding alcohols that are incorporated into lignins.
Catalytic activity	S-adenosyl-L-methionine + 3,4-dihydroxy-trans-cinnamate = S-adenosyl-L-homocysteine + 3-methoxy-4-hydroxy-trans-cinnamate.
Pathway	Aromatic compound metabolism; phenylpropanoid biosynthesis.
Subunit structure	Homodimer. Ref.2
Tissue specificity	More abundant in roots and stems.
Induction	By infection, plant wounding, or elicitor treatment of cell cultures.
Sequence similarities	Belongs to the methyltransferase superfamily. Type 2 family. COMT subfamily.

Ontologies

Keywords
Biological process	Lignin biosynthesis
Ligand	S-adenosyl-L-methionine
Molecular function	Methyltransferase Transferase
Technical term	3D-structure
Gene Ontology (GO)
Biological process	lignin biosynthetic process Inferred from electronic annotation. Source: UniProtKB-KW
Molecular function	caffeate O-methyltransferase activity Inferred from electronic annotation. Source: EC protein dimerization activity Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Chain

1 – 365

365

Caffeic acid 3-O-methyltransferase

PRO_0000063204

Regions

Region

130 – 136

7

Substrate binding

Region

162 – 180

19

Substrate binding

Sites

Active site

269

1

Proton acceptor

Binding site

208

1

S-adenosyl-L-methionine; via carbonyl oxygen

Binding site

231

1

S-adenosyl-L-methionine

Binding site

251

1

S-adenosyl-L-methionine

Binding site

252

1

S-adenosyl-L-methionine; via amide nitrogen

Binding site

265

1

S-adenosyl-L-methionine

Secondary structure

1

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

365

Helix Strand Turn

Details...

Helix

16 – 27

12

Turn

28 – 30

3

Helix

31 – 42

12

Helix

44 – 49

6

Helix

59 – 63

5

Helix

73 – 86

14

Beta strand

89 – 96

8

Beta strand

102 – 108

7

Helix

110 – 114

5

Helix

125 – 131

7

Helix

134 – 140

7

Helix

143 – 149

7

Helix

153 – 158

6

Helix

162 – 168

7

Helix

170 – 191

22

Turn

192 – 194

3

Beta strand

202 – 207

6

Turn

210 – 212

3

Helix

214 – 221

8

Beta strand

225 – 231

7

Helix

233 – 236

4

Beta strand

245 – 249

5

Turn

252 – 254

3

Beta strand

265 – 267

3

Helix

268 – 270

3

Helix

273 – 286

14

Beta strand

289 – 291

3

Beta strand

293 – 297

5

Helix

308 – 323

16

Beta strand

324 – 326

3

Helix

332 – 341

10

Beta strand

347 – 353

7

Beta strand

356 – 361

6

Sequences

	Sequence		Length	Mass (Da)
	P28002-1 [UniParc]. Last modified August 1, 1992. Version 1. Checksum: C14B0D75F979C6B6	FASTA	365	39,946
	10 20 30 40 50 60 MGSTGETQIT PTHISDEEAN LFAMQLASAS VLPMILKSAL ELDLLEIIAK AGPGAQISPI 70 80 90 100 110 120 EIASQLPTTN PDAPVMLDRM LRLLACYIIL TCSVRTQQDG KVQRLYGLAT VAKYLVKNED 130 140 150 160 170 180 GVSISALNLM NQDKVLMESW YHLKDAVLDG GIPFNKAYGM TAFEYHGTDP RFNKVFNKGM 190 200 210 220 230 240 SDHSTITMKK ILETYTGFEG LKSLVDVGGG TGAVINTIVS KYPTIKGINF DLPHVIEDAP 250 260 270 280 290 300 SYPGVEHVGG DMFVSIPKAD AVFMKWICHD WSDEHCLKFL KNCYEALPDN GKVIVAECIL 310 320 330 340 350 360 PVAPDSSLAT KGVVHIDVIM LAHNPGGKER TQKEFEDLAK GAGFQGFKVH CNAFNTYIME FLKKV

References

[1]	"Stress responses in alfalfa (Medicago sativa L). X. Molecular cloning and expression of S-adenosyl-L-methionine:caffeic acid 3-O-methyltransferase, a key enzyme of lignin biosynthesis." Gowri G., Bugos R.C., Campbell W.H., Maxwell C.A., Dixon R.A. Plant Physiol. 97:7-14(1991) [PubMed: 16668418] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA]. Strain: cv. Apollo.
[2]	"Structural basis for the modulation of lignin monomer methylation by caffeic acid/5-hydroxyferulic acid 3/5-O-methyltransferase." Zubieta C., Kota P., Ferrer J.-L., Dixon R.A., Noel J.P. Plant Cell 14:1265-1277(2002) [PubMed: 12084826] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (2.2 ANGSTROMS) IN COMPLEX WITH SUBSTRATES, SUBUNIT.

Cross-references

Sequence databases

EMBLGenBankDDBJ

M63853 mRNA. Translation: AAB46623.1.

PIR

T09673.

3D structure databases

PDBPDBe

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1KYW	X-ray	2.40	A/C/F	1-365	[»]
1KYZ	X-ray	2.20	A/C/E	1-365	[»]

ModBase

Search...

Enzyme and pathway databases

BRENDA

2.1.1.68. 815.

Family and domain databases

InterPro

IPR016461. O-MeTrfase_COMT_euk.
IPR001077. O_MeTrfase_2.
IPR012967. Plant_MeTrfase_dimerisation.
[Graphical view]

Pfam

PF08100. Dimerisation. 1 hit.
PF00891. Methyltransf_2. 1 hit.
[Graphical view]

PIRSF

PIRSF005739. O-mtase. 1 hit.

ProtoNet

Search...

Entry information

Entry name

COMT1_MEDSA

Accession

Primary (citable) accession number: P28002

Entry history

Integrated into UniProtKB/Swiss-Prot:	August 1, 1992
Last sequence update:	August 1, 1992
Last modified:	January 20, 2009
This is version 59 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

PPAP (Plant Proteome Annotation Project)