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Title
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Nucleoside binding site of herpes simplex type 1 thymidine kinase analyzed by X-ray crystallography.
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Authors
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J.Vogt,
R.Perozzo,
A.Pautsch,
A.Prota,
P.Schelling,
B.Pilger,
G.Folkers,
L.Scapozza,
G.E.Schulz.
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Ref.
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Proteins, 2000,
41,
545-553.
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PubMed id
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Abstract
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The crystal structures of the full-length Herpes simplex virus type 1 thymidine
kinase in its unligated form and in a complex with an adenine analogue have been
determined at 1.9 A resolution. The unligated enzyme contains four water
molecules in the thymidine pocket and reveals a small induced fit on substrate
binding. The structure of the ligated enzyme shows for the first time a bound
adenine analogue after numerous complexes with thymine and guanine analogues
have been reported. The adenine analogue constitutes a new lead compound for
enzyme-prodrug gene therapy. In addition, the structure of mutant Q125N
modifying the binding site of the natural substrate thymidine in complex with
this substrate has been established at 2.5 A resolution. It reveals that neither
the binding mode of thymidine nor the polypeptide backbone conformation is
altered, except that the two major hydrogen bonds to thymidine are replaced by a
single water-mediated hydrogen bond, which improves the relative acceptance of
the prodrugs aciclovir and ganciclovir compared with the natural substrate.
Accordingly, the mutant structure represents a first step toward improving the
virus-directed enzyme-prodrug gene therapy by enzyme engineering.
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