Characterization of N-malonylurea hydrolase in the pyrimidine oxidative degradation pathway of Rhodococcus erythropolis JCM 3132.

Abstract

Rhodococcus erythropolis JCM 3132 has the pyrimidine oxidative pathway consisting of uracil/thymine dehydrogenase, barbiturase, and N-malonylurea hydrolase (ureidomalonase, EC 3.5.1.95). In this study, we successfully purified to homogeneity a functional protein from Escherichia coli Rosetta2 (DE3) overexpressing the N-malonylurea hydrolase gene from R. erythropolis JCM3132, and the purified enzyme showed the activity of amide hydrolysis of malonuric acid (ureidomalonic acid) to urea and malonic acid. The enzyme was also shown to have a strict specificity toward malonuric acid. The optimal reaction pH and temperature were 8.5 and 40 °C, respectively. Importantly, gene expression of the gene cluster of the pyrimidine oxidative degradation pathway was shown to be inducible by the addition of uracil. Pyrimidine oxidative degradation could be useful in the equilibrium control of ribose transfer between pyrimidine and purine bases, with an increase in the conversion yield of purine nucleoside synthesis.