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Active site geometry of oxalate decarboxylase from Flammulina velutipes: Role of histidine coordinated manganese in substrate recognition

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Title Active site geometry of oxalate decarboxylase from Flammulina velutipes: Role of histidine coordinated manganese in substrate recognition
 
Creator Chakraborty, Subhra
Chakraborty, Niranjan
Jain, Deepti
Salunke, Dinakara M
Datta, Asis
 
Subject Oxalate decarboxylase
ECM protein
germin motif
knowledge-based modeling
knockout mutants
 
Description Oxalate decarboxylase (OXDC) from the wood-rotting fungus Flammulina velutipes, which catalyzes the
conversion of oxalate to formic acid and CO2 in a single-step reaction, is a duplicated double-domain germin
family enzyme. It has agricultural as well as therapeutic importance. We reported earlier the purification and
molecular cloning of OXDC. Knowledge-based modeling of the enzyme reveals a ␤-barrel core in each of
the two domains organized in the hexameric state. A cluster of three histidines suitably juxtaposed to
coordinate a divalent metal ion exists in both the domains. Involvement of the two histidine clusters in the
catalytic mechanism of the enzyme, possibly through coordination of a metal cofactor, has been hypoth-
esized because all histidine knockout mutants showed total loss of decarboxylase activity. The atomic
absorption spectroscopy analysis showed that OXDC contains Mn2+ at up to 2.5 atoms per subunit. Docking
of the oxalate in the active site indicates a similar electrostatic environment around the substrate-binding site
in the two domains. We suggest that the histidine coordinated manganese is critical for substrate recognition
and is directly involved in the catalysis of the enzyme.
This work was supported by grants from the Department of Biotechnology, Government of India.
 
Date 2013-10-18T06:00:06Z
2013-10-18T06:00:06Z
2002
6 June 2002
 
Type Article
 
Identifier Protein Sci., 11: 2138-2147
http://hdl.handle.net/123456789/24
 
Language en
 
Publisher Cold Spring Harbor Laboratory Press