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.