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-pyrone-4,6-dicarboxylate lactonase (LigI)
Identifiers
EC no.3.1.1.57
CAS no.84177-55-9
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
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NCBIproteins
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

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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]

References

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  1. ^ "syringate degradation". MetaCyc. SRI International.
  2. ^ "protocatechuate degradation I (meta-cleavage pathway)". MetaCyc. SRI International.
  3. ^ 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

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