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

摘要

Myxococcus xanthus Nudix hydrolase 2 (Nud2) hydrolyzed oxidized deoxynucleotides, such as 8-oxo-dGTP, 8-oxo-dGDP, 8-OH -d P, and 2-OH - d ATP, and showed the highest specific activity toward 8-oxo-dGTP. Mn2+ was the most effective cofactor 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 ((84)AX(5) (90)GX(7) REX2 EEXGX). Replacement of Ala84 and/or Gly90 in the Nudix motif of Nud2 by Gly or (au 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.