Demonstration and partial characterization of ecto-ATPase in Balamuthia mandrillaris and its possible role in the host-cell interactions

Aims: To investigate the presence and partial characterization of ecto-ATPase in Balamuthia mandrillaris. Methods and Results: In vitro assays were used to demonstrate that live B. mandrillaris hydrolyses extracellular ATP. Using nondenaturing polyacrylamide gel electrophoresis, B. mandrillaris exhibited a single ecto-ATPase band of molecular mass of more than 545 kDa. This ecto-ATPase was insensitive to ouabain, levamisole, sodium azide and sodium orthovanadate but stimulated by MgCl2. The ecto-ATPase was heat stable, but labile to detergent, sodium dodecyl sulphate. Suramin, an antagonist of P2 purinoreceptors and an inhibitor of some ecto-ATPases, inhibited B. mandrillaris binding to and cytotoxicity of HBMEC (human brain microvascular endothelial cello), in vitro. Conclusions: For the first time, we describe that live B. mandrillaris hydrolyses extracellular ATP and exhibits a > 545kDa ecto-ATPase. Significance and Impact of the Study: This surface enzyme may play a role in the salvage of purines from the extracellular medium and may be important for the pathogenesis of B. mandrillaris.