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PDBsum entry 4e2s
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References listed in PDB file
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Key reference
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Title
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Structural and functional insights into (s)-Ureidoglycine aminohydrolase, Key enzyme of purine catabolism in arabidopsis thaliana.
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Authors
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I.Shin,
R.Percudani,
S.Rhee.
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Ref.
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J Biol Chem, 2012,
287,
18796-18805.
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PubMed id
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Abstract
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The ureide pathway has recently been identified as the metabolic route of purine
catabolism in plants and some bacteria. In this pathway, uric acid, which is a
major product of the early stage of purine catabolism, is degraded into
glyoxylate and ammonia via stepwise reactions of seven different enzymes.
Therefore, the pathway has a possible physiological role in mobilization of
purine ring nitrogen for further assimilation. (S)-Ureidoglycine aminohydrolase
enzyme converts (S)-ureidoglycine into (S)-ureidoglycolate and ammonia,
providing the final substrate to the pathway. Here, we report a structural and
functional analysis of this enzyme from Arabidopsis thaliana (AtUGlyAH). The
crystal structure of AtUGlyAH in the ligand-free form shows a monomer structure
in the bicupin fold of the β-barrel and an octameric functional unit as well as
a Mn(2+) ion binding site. The structure of AtUGlyAH in complex with
(S)-ureidoglycine revealed that the Mn(2+) ion acts as a molecular anchor to
bind (S)-ureidoglycine, and its binding mode dictates the enantioselectivity of
the reaction. Further kinetic analysis characterized the functional roles of the
active site residues, including the Mn(2+) ion binding site and residues in the
vicinity of (S)-ureidoglycine. These analyses provide molecular insights into
the structure of the enzyme and its possible catalytic mechanism.
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