Enzymatic properties of the mouse Mx1 protein-associated GTPase

Abstract

Murine Mx1 protein, an interferon-inducible nuclear protein present in inbred mouse Mx + strains, confers resistance to influenza virus infection. The purified Mx1 protein was found to carry the activities of both GTPase and GTP-binding. Enzymatic properties of the Mx1-associated GTPase were examined using the Mx1 protein purified from Escherichia coli expressing Mx1 cDNA. The Mxl protein exhibited a substrate preference for GTP. The V max of ATP hydrolysis was about 7.6% the rate of GTP hydrolysis. The hydrolysis of CTP and UTP was virtually negligible. The K m for GTP hydrolysis was 667 μM and the rate was 13.8 mol GTP hydrolysis per min per mol Mx1 protein. The enzymatic properties of Mx1 protein-associated GTPase were compared with those of the GTPase super-gene family and the Mx-related family.