Heterodimeric V. nikolskii phospholipases A2 induce aggregation of the lipid bilayer

- Heterodimeric PLA2s from V. Nikolskii (HDP) cause aggregation of lipid bilayers.
- HDPs put bilayers together, because both subunits contain a membrane-binding site.
- The aggregation occurs for negatively charged lipid, phosphatidylglycerol.
- The aggregation does not occur for neutral lipid phosphatidylcholine.
- The aggregation does not depend on the presence of Ca2+.

We report that the action of the heterodimeric phospholipases A2 (PLA2s) from Vipera nikolskii, which comprises enzymatically active basic subunit and inactive acidic PLA2 homologue, on the lipid bilayer results in the aggregation and stacking of bilayers. These processes are demonstrated using two independent methods (fluorescence spectroscopy and electron microscopy). Aggregation of bilayers is possible because both subunits of the V. nikolskii heterodimer contain a membrane-binding site (also known as IBS). Thus, when the two IBSs bind to the membrane, the heterodimer acts as a connecting agent. Heterodimers induce aggregation of negatively charged bilayers composed of phosphatidylglycerol and do not induce aggregation of neutral bilayers composed of phosphatidylcholine.

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