Journal of Helminthology

Table of Contents - September 2012 - Volume 86, Issue 03  

Research Papers

Molecular and catalytic properties of an arginine kinase from the nematode Ascaris suum

M. Nagatakia1, K. Udaa2, B.R. Jarillaa1, S. Tokuhiroa1, S. Wickramasinghea1, T. Suzukia2, D. Blaira3 and T. Agatsumaa1 c1

a1 Department of Environmental Health Sciences, Kochi Medical School, Oko, Nankoku City, Kochi 783-8505, Japan

a2 Laboratory of Biochemistry, Faculty of Science, Kochi University, Kochi, 780-8520, Japan

a3 School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia

Abstract

We amplified the cDNA coding for arginine kinase (AK) from the parasitic nematode Ascaris suum, cloned it in pMAL plasmid and expressed the enzyme as a fusion protein with the maltose-binding protein. The whole cDNA was 1260 bp, encoding 400 amino acids, and the recombinant protein had a molecular mass of 45,341 Da. Ascaris suum recombinant AK showed significant activity and strong affinity ( K _{m}^{Arg} = 0.126\hairsp mM) for the substrate l-arginine. It also exhibited high catalytic efficiency ( k _{cat}/ K _{m}^{Arg} = 352) comparable with AKs from other organisms. Sequence analysis revealed high amino acid sequence identity between A. suum AK and other nematode AKs, all of which cluster in a phylogenetic tree. However, comparison of gene structures showed that A. suum AK gene intron/exon organization is quite distinct from that of other nematode AKs. Phosphagen kinases (PKs) from certain parasites have been shown to be potential novel drug targets or tools for detection of infection. The characterization of A. suum AK will be useful in the development of strategies for control not only of A. suum but also of related species infecting humans.

(Received December 19 2010)

(Accepted June 13 2011)

(Online publication July 25 2011)

Correspondence:

c1 Fax: +81 88 880 2535 E-mail: agatsuma@kochi-u.ac.jp