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PDBsum entry 1w5r
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References listed in PDB file
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Key reference
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Title
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Investigation of the catalytic triad of arylamine n-Acetyltransferases: essential residues required for acetyl transfer to arylamines.
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Authors
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J.Sandy,
A.Mushtaq,
S.J.Holton,
P.Schartau,
M.E.Noble,
E.Sim.
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Ref.
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Biochem J, 2005,
390,
115-123.
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PubMed id
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Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
percentage match of
96%.
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Abstract
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The NATs (arylamine N-acetyltransferases) are a well documented family of
enzymes found in both prokaryotes and eukaryotes. NATs are responsible for the
acetylation of a range of arylamine, arylhydrazine and hydrazine compounds. We
present here an investigation into the catalytic triad of residues (Cys-His-Asp)
and other structural features of NATs using a variety of methods, including
site-directed mutagenesis, X-ray crystallography and bioinformatics analysis, in
order to investigate whether each of the residues of the catalytic triad is
essential for catalytic activity. The catalytic triad of residues, Cys-His-Asp,
is a well defined motif present in several families of enzymes. We mutated each
of the catalytic residues in turn to investigate the role they play in
catalysis. We also mutated a key residue, Gly126, implicated in acetyl-CoA
binding, to examine the effects on acetylation activity. In addition, we have
solved the structure of a C70Q mutant of Mycobacterium smegmatis NAT to a
resolution of 1.45 A (where 1 A=0.1 nm). This structure confirms that the
mutated protein is correctly folded, and provides a structural model for an
acetylated NAT intermediate. Our bioinformatics investigation analysed the
extent of sequence conservation between all eukaryotic and prokaryotic NAT
enzymes for which sequence data are available. This revealed several new
sequences, not yet reported, of NAT paralogues. Together, these studies have
provided insight into the fundamental core of NAT enzymes, and the regions where
sequence differences account for the functional diversity of this family. We
have confirmed that each of the three residues of the triad is essential for
acetylation activity.
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