Journal article ยท Preprint article
Arrangement of Annexin A2 tetramer and its impact on the structure and diffusivity of supported lipid bilayers
Colloids and Biological Interfaces Group, Self-organizing materials for nanotechnology Section, Department of Micro- and Nanotechnology, Technical University of Denmark1
Self-organizing materials for nanotechnology Section, Department of Micro- and Nanotechnology, Technical University of Denmark2
Department of Micro- and Nanotechnology, Technical University of Denmark3
Annexins are a family of proteins that bind to anionic phospholipid membranes in a Ca2+-dependent manner. Annexin A2 forms heterotetramers (Anx A2t) with the S100A10 (p11) protein dimer. The tetramer is capable of bridging phospholipid membranes and it has been suggested to play a role in Ca2+-dependent exocytosis and cell-cell adhesion of metastatic cells.
Here, we employ X-ray reflectivity measurements to resolve the conformation of Anx A2t upon Ca2+-dependent binding to single supported lipid bilayers (SLBs) composed of different mixtures of anionic (POPS) and neutral (POPC) phospholipids. Based on our results we propose that Anx A2t binds in a side-by-side configuration, i.e., both Anx A2 monomers bind to the bilayer with the p11 dimer positioned on top.
Furthermore, we observe a strong decrease of lipid mobility upon binding of Anx A2t to SLBs with varying POPS content. X-Ray reflectivity measurements indicate that binding of Anx A2t also increases the density of the SLB. Interestingly, in the protein-facing leaflet of the SLB the lipid density is higher than in the substrate-facing leaflet.
This asymmetric densification of the lipid bilayer by Anx A2t and Ca2+ might have important implications for the biochemical mechanism of Anx A2t-induced endo- and exocytosis.
Language: | English |
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Year: | 2010 |
Pages: | 4084-4094 |
ISSN: | 17446848 , 1744683x and 09599428 |
Types: | Journal article and Preprint article |
DOI: | 10.1039/c0sm00047g |