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High-speed atomic force microscopy shows that annexin V stabilizes membranes on the second timescale. Annexins are abundant cytoplasmic proteins that can bind to negatively charged phospholipids in a Ca2+-dependent manner, and are known to play a role in the storage of Ca2+ and membrane healing. Little is known, however, about the dynamic processes of protein– Ca2+–membrane assembly and disassembly. Here we show that high-speed atomic force microscopy (HS-AFM) can be used to repeatedly induce and disrupt annexin assemblies and study their structure, dynamics and interactions. Our HS-AFM set-up is adapted for such biological applications through the integration of a pumping system for buffer exchange and a pulsed laser system for uncaging caged compounds. We find that biochemically identical annexins (annexin V) display different effective Ca2+ and membrane affinities depending on the assembly location, providing a wide Ca2+ buffering regime while maintaining membrane stabilization. We also show that annexin is membrane-recruited and forms stable supramolecular assemblies within ∼5 s in conditions that are comparable to a membrane lesion in a cell. Molecular dynamics simulations provide atomic detail of the role played by Ca2+ in the reversible binding of annexin to the membrane surface. Nature Nanotechnology, 2016.

Recent publications

Miyagi, A.; Chipot, C.; Rangl, M.; Scheuring, S.
High-speed atomic force microscopy shows that annexin V stabilizes membranes on the second timescale
Nature Nanotechnology

2016,  (), .
dx.doi.org

Ramadoss, V.; Dehez, F.; Chipot, C
AlaScan: A graphical user interface for alanine scanning free–energy calculations.
J. Chem. Info. Model.

2016,  (56), 1122-1126.
dx.doi.org

Lee, C. T.; Comer, J.; Herndon, C.; Leung, N.; Pavlova, A.; Swift, R. V.; Tung, C.; Rowley, C. N.; Amaro, R. E.; Chipot, C.; Wang, Y.; Gumbart, J. C.
Simulation-Based Approaches for Determining Membrane Permeability of Small Compounds.
J. Chem. Inf. Model.

2016,  (56), 721-733.
dx.doi.org

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