Cross-linking of phospholipid membranes is a conserved property of calcium-sensitive synaptotagmins

Connell , Emma and Giniatullina, Asiya and Lai-Kee-Him, Joséphine and Tavare, Richard and Ferrari, Enrico and Roseman, Alan and Cojoc, Dan and Brisson, Alain R. and Davletov, Bazbek (2008) Cross-linking of phospholipid membranes is a conserved property of calcium-sensitive synaptotagmins. Journal of molecular biology, 380 (1). pp. 42-50. ISSN 0022-2836

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Official URL: http://dx.doi.org/10.1016/j.jmb.2008.01.084

Abstract

Synaptotagmins are vesicular proteins implicated in many membrane trafficking events. They are highly conserved in evolution and the mammalian family contains 16 isoforms. We now show that the tandem C2 domains of several calcium-sensitive synaptotagmin isoforms tested, including Drosophila synaptotagmin, rapidly cross-link phospholipid membranes. In contrast to the tandem structure, individual C2 domains failed to trigger membrane cross-linking in several novel assays. Large-scale liposomal aggregation driven by tandem C2 domains in response to calcium was confirmed by the following techniques: turbidity assay, dynamic light-scattering and both confocal and negative stain electron microscopy. Firm cross-linking of membranes was evident from laser trap experiments. High-resolution cryo-electron microscopy revealed that membrane cross-linking by tandem C2 domains results in a constant distance of ∼9 nm between the apposed membranes. Our findings show the conserved nature of this important property of synaptotagmin, demonstrate the significance of the tandem C2 domain structure and provide a plausible explanation for the accelerating effect of synaptotagmins on membrane fusion.

Item Type:Article
Keywords:C2 domain, membrane cross-linking, synaptotagmin, electron microscopy, laser trap
Subjects:C Biological Sciences > C700 Molecular Biology, Biophysics and Biochemistry
Divisions:College of Science > School of Life Sciences
ID Code:6610
Deposited By: Enrico Ferrari
Deposited On:20 Oct 2012 11:46
Last Modified:15 Nov 2013 16:59

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