Overexpression of human N-myristoyltransferase utilizing a T7 polymerase gene expression system.

Myristoyl CoA:protein N-myristoyltransferase catalyzes the addition of myristate to the amino-terminal glycine residue of a number of eukaryotic proteins. The gene encoding human N-myristoyltransferase (hNMT) was cloned into the overexpression vector pT7-7 which utilizes the T7 RNA polymerase gene expression system. The hNMT enzyme was purified to near homogeneity with more than 95% recovery using a single-step purification method involving SP-Sepharose fast flow column chromatography. The specific activity of the purified NMT was 220 nmol/min/mg of protein in the presence of oncoprotein-derived peptide substrate pp60src. The hNMT exhibited an apparent molecular weight of 49 kDa on SDS-polyacrylamide gel electrophoresis. Antibodies to Escherichia coli-expressed hNMT specifically recognize hNMT from crude bacterial lysates. The over-expressed hNMT was homogeneous and showed enzyme activity.