Molecular characterization of a cDNA-derived phosphagen kinase from Biomphalaria glabrata, the intermediate host of Schistosoma mansoni

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The present study contains the first description of phosphagen kinase (PK) from the intermediate snail host, Biomphalaria glabrata. We determined the cDNA sequence of PK from the snail B. glabrata, a vector of Schistosoma mansoni, and then cloned the cDNA into a pMAL plasmid and expressed it in Escherichia coli as a fusion protein with maltose-binding protein (MBP). The recombinant protein, consisting of 353 amino acids, has a calculated molecular mass of 39,376 Da and an estimated isoelectric point (pI) of 6.12. B. glabrata PK showed significant activity with the substrate L-arginine, indicating AK, and has the following kinetic constants determined for the forward reaction: KmArg=0.26 mM, KdArg=0.28 mM, kcat=20.3 s-1 and Vmax=30.4 μmol Pi/min/mg protein. Comparison of kcat/KmArg values with other AKs indicates that B. glabrata AK has a high catalytic efficiency (78.12 s-1 mM-1), although it exhibited weak synergism during substrate binding (KdArg/KmArg=1.08). In view of the significance of AK in temporal energy buffering, this enzyme may be a novel molluscicide target to control B. glabrata and consequently control the transmission of schistosomiasis.
日本衛生動物学会の論文