Enzymatic characteristics of Nudix hydrolase 2 (Nud2), an 8-oxo-dGTP hydrolase from Myxococcus xanthus

Abstract

Myxococcus xanthus Nudix hydrolase 2 (Nud2) hydrolyzed oxidized deoxynucleotides, such as 8-oxo-dGTP, 8-oxo-dGDP, 8-OH-dTP, and 2-OH-dATP, and showed the highest specific activity toward 8-oxo-dGTP. Mn²⁺ was the most effective co-factor for stimulating oxidized deoxynucleotide hydrolase activity. The K_m of Nud2 with 8-oxo-dGTP for Mn²⁺ was 19-fold lower than that for Mg²⁺, and was 2-fold lower than that with dGTP for Mn²⁺. The specificity constant (k_cat/K_m) for 8-oxo-dGTP was 6-fold higher than that for dGTP. Nud2 contains a similar Nudix motif (⁸⁴AX₅⁹⁰GX₇REX₂EEXGX). Replacement of Ala84 and/or Gly90 in the Nudix motif of Nud2 by Gly or Glu had negligible effects on 8-oxo-dGTP hydrolase activity, suggesting that a strict Nudix motif sequence is not essential for complete hydrolase activity of Nud2.