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Active site closure facilitates juxtaposition of reactant atoms for initiation of catalysis by human dUTPase
Author(s) -
Varga Balázs,
Barabás Orsolya,
Kovári Júlia,
Tóth Judit,
Hunyadi-Gulyás Éva,
Klement Éva,
Medzihradszky Katalin F.,
Tölgyesi Ferenc,
Fidy Judit,
Vértessy Beáta G.
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.09.005
Subject(s) - van der waals force , chemistry , active site , substrate (aquarium) , nucleophile , catalysis , binding site , stereochemistry , biochemistry , molecule , biology , ecology , organic chemistry
Human dUTPase, essential for DNA integrity, is an important survival factor for cancer cells. We determined the crystal structure of the enzyme:α,β‐imino‐dUTP:Mg complex and performed equilibrium binding experiments in solution. Ordering of the C‐terminus upon the active site induces close juxtaposition of the incoming nucleophile attacker water oxygen and the α‐phosphorus of the substrate, decreasing their distance below the van der Waals limit. Complex interactions of the C‐terminus with both substrate and product were observed via a specifically designed tryptophan sensor, suitable for further detailed kinetic and ligand binding studies. Results explain the key functional role of the C‐terminus.