Mechanism of phosphoryl transfer by nucleoside diphosphate kinase pH dependence and role of the active site Lys16 and Tyr56 residues.
Nucleoside diphosphate (NDP) kinase phosphorylates nucleoside diphosphates with little specificity for the base and the sugar. Although nucleotide analogues used in antiviral therapies are also metabolized to their triphosphate form by NDP kinase, their lack of the 3'-hydroxyl of the ribose, which allows them to be DNA chain terminators, severely impairs the catalytic efficiency of NDP kinase. We have analyzed the kinetics parameters of several mutant NDP kinases modified on residues (Lys16, Tyr56, Asn119) interacting with the gamma-phosphate and/or the 3'-OH of the Mg2+-ATP substrate. We compared the relative contributions of the active-site residues and the substrate 3'-OH for point mutations on Lys16, Tyr56 and Asn119. Analysis of additional data from pH profiles identify the ionization state of these residues in the enzyme active form. X-ray structure of K16A mutant NDP kinase shows no detectable rearrangement of the residues of the active site.
Unité de Régulation Enzymatique des Activités Cellulaires, CNRS URA 1773, Institut Pasteur, Paris, France.
B
B
Schneider
M
M
Babolat
Y W
YW
Xu
J
J
Janin
M
M
Véron
D
D
Deville-Bonne
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001216:Asparagine / Q000378:metabolism; D002384:Catalysis; D018360:Crystallography, X-Ray; D004023:Dictyostelium / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008239:Lysine / Q000378:metabolism*; D008956:Models, Chemical; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009701:Nucleoside-Diphosphate Kinase / Q000235:genetics / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000378:metabolism*
D010758:Phosphorus; D014443:Tyrosine; D001216:Asparagine; D000255:Adenosine Triphosphate; D009701:Nucleoside-Diphosphate Kinase; D008239:Lysine