The enzyme 2-pyrone-4,6-dicarboxylate lactonase (EC 3.1.1.57, LigI) catalyzes the reversible hydrolytic reaction
| 2-pyrone-4,6-dicarboxylate lactonase (LigI) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 3.1.1.57 | ||||||||
| CAS no. | 84177-55-9 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
- 2-oxo-2H-pyran-4,6-dicarboxylate + H2O = (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate
This enzyme belongs to the Amidohydrolase superfamily of enzymes and is a member of Cluster of Orthologous Groups (COG) 3618. The systematic name of this enzyme is 2-oxo-2H-pyran-4,6-dicarboxylate lactonohydrolase. This enzyme is found to play an important role in the metabolism of lignin-derived aromatic compounds in both the syringate degradation pathway[1] and the protocatechuate 4,5-cleavage pathway.[2]
LigI from Sphingomonas is of particular interest as it has been shown to be the first member of the amidohydrolase superfamily to not require a divalent metal cation for catalytic activity.[3]
Mechanism
editThe mechanism of catalysis of LigI has been determined by crystallography and NMR analysis. More specifically, the hydrolytic water molecule is activated by the transfer of a proton to Asp-248 whereas the carbonyl group of the 2-pyrone-4,6-dicarboxylate (PDC) lactone substrate is activated by hydrogen bonding interactions with His-180, His-31, and His-33.[3]
References
edit- ^ "syringate degradation". MetaCyc. SRI International.
- ^ "protocatechuate degradation I (meta-cleavage pathway)". MetaCyc. SRI International.
- ^ a b Hobbs ME, Malashkevich V, Williams HJ, Xu C, Sauder JM, Burley SK, Almo SC, Raushel FM (April 2012). "Structure and Catalytic Mechanism of LigI: Insight into the Amidohydrolase Enzymes of cog3618 and Lignin Degradation". Biochemistry. 51 (16): 3497–507. doi:10.1021/bi300307b. PMC 3416963. PMID 22475079.
Further reading
edit- Kersten PJ, Dagley S, Whittaker JW, Arciero DM, Lipscomb JD (1982). "2-pyrone-4,6-dicarboxylic acid, a catabolite of gallic acids in Pseudomonas species". J. Bacteriol. 152 (3): 1154–62. doi:10.1128/jb.152.3.1154-1162.1982. PMC 221622. PMID 7142106.
- Maruyama K (February 1983). "Purification and properties of 2-pyrone-4,6-dicarboxylate hydrolase". J. Biochem. 93 (2): 557–65. doi:10.1093/oxfordjournals.jbchem.a134210. PMID 6841353.
