title: Active site closure facilitates juxtaposition of reactant atoms for initiation of catalysis by human dUTPase.
abstract: Human dUTPase, essential for DNA integrity, is an important survival factor for cancer cells. We determined the crystal structure of the enzyme:alpha,beta-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 alpha-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.
authors: Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Hungary.
authors: Balázs
authors: B
authors: Varga
authors: Orsolya
authors: O
authors: Barabás
authors: Júlia
authors: J
authors: Kovári
authors: Judit
authors: J
authors: Tóth
authors: Eva
authors: E
authors: Hunyadi-Gulyás
authors: Eva
authors: E
authors: Klement
authors: Katalin F
authors: KF
authors: Medzihradszky
authors: Ferenc
authors: F
authors: Tölgyesi
authors: Judit
authors: J
authors: Fidy
authors: Beáta G
authors: BG
authors: Vértessy
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011755:Pyrophosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D008024:Ligands; D021122:Protein Subunits; D011755:Pyrophosphatases; C020020:dUTP pyrophosphatase