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PDBsum entry 5dqv
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DOI no:
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J Struct Biol
195:113-122
(2016)
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PubMed id:
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Structural and biochemical characterization of bacterial YpgQ protein reveals a metal-dependent nucleotide pyrophosphohydrolase.
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Y.J.Jeon,
S.C.Park,
W.S.Song,
O.H.Kim,
B.C.Oh,
S.I.Yoon.
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ABSTRACT
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The optimal balance of cellular nucleotides and the efficient elimination of
non-canonical nucleotides are critical to avoiding erroneous mutation during DNA
replication. One such mechanism involves the degradation of excessive or
abnormal nucleotides by nucleotide-hydrolyzing enzymes. YpgQ contains the
histidine-aspartate (HD) domain that is involved in the hydrolysis of
nucleotides or nucleic acids, but the enzymatic activity and substrate
specificity of YpgQ have never been characterized. Here, we unravel the
catalytic activity and structural features of YpgQ to report the first
Mn(2+)-dependent pyrophosphohydrolase that hydrolyzes (deoxy)ribonucleoside
triphosphate [(d)NTP] to (deoxy)ribonucleoside monophosphate and pyrophosphate
using the HD domain. YpgQ from Bacillus subtilis (bsYpgQ) displays a helical
structure and assembles into a unique dimeric architecture that has not been
observed in other HD domain-containing proteins. Each bsYpgQ monomer
accommodates a metal ion and a nucleotide substrate in a cavity located between
the N- and C-terminal lobes. The metal cofactor is coordinated by the canonical
residues of the HD domain, namely, two histidine residues and two aspartate
residues, and is positioned in close proximity to the β-phosphate group of the
nucleotide, allowing us to propose a nucleophilic attack mechanism for the
nucleotide hydrolysis reaction. YpgQ enzymes from other bacterial species also
catalyze pyrophosphohydrolysis but exhibit different substrate specificity.
Comparative structural and mutational studies demonstrated that residues outside
the major substrate-binding site of bsYpgQ are responsible for the
species-specific substrate preference. Taken together, our structural and
biochemical analyses highlight the substrate-recognition mode and catalysis
mechanism of YpgQ in pyrophosphohydrolysis.
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}
}
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