2-pyrone-4,6-dicarboxylate lactonase

The enzyme 2-pyrone-4,6-dicarboxylate lactonase (EC 3.1.1.57, LigI) catalyzes the reversible hydrolytic reaction

2-oxo-2H-pyran-4,6-dicarboxylate + H₂O = (1E)-4-oxobut-1-ene-1,2,4-tricarboxylate

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
Search PMC articles PubMed articles NCBI proteins

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

The 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]