Reaction of human UMP‐CMP kinase with natural and analog substrates

• Published in: European Journal of Biochemistry Vol. 270; no. 8; pp. 1784 - 1790
• Main Authors: Pasti, Claudia, Gallois‐Montbrun, Sarah, Munier‐Lehmann, Hélène, Veron, Michel, Gilles, Anne‐Marie, Deville‐Bonne, Dominique
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.04.2003; Wiley
• Subjects: 3TC; antiviral analog; AraC; Base Sequence; Cloning, Molecular; Cytidine Monophosphate - metabolism; DNA Primers; Humans; Kinetics; Life Sciences; Molecular Sequence Data; Nucleoside-Phosphate Kinase - genetics; Nucleoside-Phosphate Kinase - isolation & purification; Nucleoside-Phosphate Kinase - metabolism; phosphorylation; Polymerase Chain Reaction; Recombinant Fusion Proteins - isolation & purification; Recombinant Fusion Proteins - metabolism; Substrate Specificity; UMP‐CMP kinase; Uridine Monophosphate - metabolism
• ISSN: 0014-2956; 1432-1033; 1432-1327
• DOI: 10.1046/j.1432-1033.2003.03537.x

UMP‐CMP kinase catalyses an important step in the phosphorylation of UTP, CTP and dCTP. It is also involved in the necessary phosphorylation by cellular kinases of nucleoside analogs used in antiviral therapies. The reactivity of human UMP‐CMP kinase towards natural substrates and nucleotide analogs was reexamined. The expression of the recombinant enzyme and conditions for stability of the enzyme were improved. Substrate inhibition was observed for UMP and CMP at concentrations higher than 0.2 mm, but not for dCMP. The antiviral analog l‐3TCMP was found to be an efficient substrate phosphorylated into l‐3TCDP by human UMP‐CMP kinase. However, in the reverse reaction, the enzyme did not catalyse the addition of the third phosphate to l‐3TCDP, which was rather an inhibitor. By molecular modelling, l‐3TCMP was built in the active site of the enzyme from Dictyostelium. Human UMP‐CMP kinase has a relaxed enantiospecificity for the nucleoside monophosphate acceptor site, but it is restricted to d‐nucleotides at the donor site.