Overview for MACiE Entry M0225
EC Number: 188.8.131.52 (A member of the Lyases, Carbon-carbon lyases, Carboxy-lyases)
Enzyme Name: adenosylmethionine decarboxylase
Biological Species: Thermotoga maritima (Bacteria)
Catalytic Chain UniprotKB Accession Codes:
- Q9WZC3 - S-adenosylmethionine decarboxylase alpha chain
Representative PDB Code: 1vr7 - CRYSTAL STRUCTURE OF S-ADENOSYLMETHIONINE DECARBOXYLASE PROENZYME(TM0655) FROM THERMOTOGA MARITIMA AT 1.2 A RESOLUTION (Resolution = 1.20 Å).
Catalytic CATH Codes:
Display structure information
Overall Comment: The proenzyme must undergo self-maturation by non-hydrolytic serinolysis. It is during this process that a pyruvoyl group (named Ser63 throughout) is formed at the C-terminus of the alpha chain.
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Stepwise Description of the Reaction
|Step 1||First step of the non-hydrolytic serinolysis process. The hydroxyl side chain of Ser63 is involved in nucleophilic attack on the main chain carbonyl of Glu62 to form an oxyoxazolidine intermediate.|
|Step 2||Part of the non-hydrolytic serinolysis process. The oxyoxazolidine intermediate rearranges to form the ester intermediate.|
|Step 3||Part of the non-hydrolytic serinolysis process. His68 deprotonates the C-alpha of Ser63 causing beta-elimination to form the C-terminus of the beta chain and the terminal dehydroalanine residue of the alpha chain.|
|Step 4||Part of the non-hydrolytic serinolysis process. The dehydroalanine residue tautomerises into an imine.|
|Step 5||Part of the non-hydrolytic serinolysis process. Water is involved in nucleophilic attack on the imine.|
|Step 6||Final step of the non-hydrolytic serinolysis process. Intramolecular elimination of ammonia to form the pyruvoyl residue.|
|Step 7||First step of Schiff base formation. The amine group is deprotonated by a base, assumed to be ammonia due to lack of further evidence.|
|Step 8||Second step of the Schiff base formation. The amine of S-adenosyl-L-methionine is involved in nucleophilic attack on the terminal carbonyl of the pyruvoyl residue.|
|Step 9||Final step of Schiff base formation. The intermediate dehydrates to form the Schiff base.|
|Step 10||The covalently attached intermediate decarboxylates and the post-translationally modified serine acts as an electron sink.|
|Step 11||Cys83 protonates the intermediate to reform the Schiff base.|
|Step 12||First step one of the hydrolysis of the Schiff base. Water is involved in nucleophilic attack on the imine.|
|Step 13||Final step the hydrolysis of the Schiff base. S-Adenosylmethioninamine is eliminated from the intermediate.|
|Step 14||His68 is deprotonated by a base, assumed to be water based on the lack of other evidence. Cys83 id re-protonated by another base, again assumed to be water.|
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Catalytic Residues Involved
||Location of Function
Post-translationally modified residue
||Main Chain Carbonyl
Post-translationally modified residue
- A. V. Toms et al. (2004), J. Biol. Chem., 279, 33837-33846. Evolutionary links as revealed by the structure of Thermotoga maritima S-adenosylmethionine decarboxylase.
- J. L. Ekstrom et al. (2001), Biochemistry, 40, 9495-9504. Structure of a human S-adenosylmethionine decarboxylase self-processing ester intermediate and mechanism of putrescine stimulation of processing as revealed by the H243A mutant.
- H. Xiong et al. (1999), Biochemistry, 38, 2462-2470. Role of cysteine-82 in the catalytic mechanism of human S-adenosylmethionine decarboxylase.
- B. I. Lee et al. (2004), J. Mol. Biol., 340, 1-7. Crystal structure of the schiff base intermediate prior to decarboxylation in the catalytic cycle of aspartate alpha-decarboxylase.
Homologue information for M0225 (1vr7)
MACiE Homologues (within the PDB)
MACiE Homologues (within UniprotKB/SwissProt)
Links to this entry in other databases