Work

Reconstituted synaptotagmin I mediates vesicle docking, priming, and fusion

Year: 2011

Type: article

Abstract: The synaptic vesicle protein synaptotagmin I (syt) promotes exocytosis via its ability to penetrate membranes in response to binding Ca(2+) and through direct interactions with SNARE proteins. However, studies using full-length (FL) membrane-embedded syt in reconstituted fusion assays have yielded conflicting results, including a lack of effect, or even inhibition of fusion, by Ca(2+). In this paper, we show that reconstituted FL syt promoted rapid docking of vesicles (<1 min) followed by a priming step (3-9 min) that was required for subsequent Ca(2+)-triggered fusion between v- and t-SNARE liposomes. Moreover, fusion occurred only when phosphatidylinositol 4,5-bisphosphate was included in the target membrane. This system also recapitulates some of the effects of syt mutations that alter synaptic transmission in neurons. Finally, we demonstrate that the cytoplasmic domain of syt exhibited mixed agonist/antagonist activity during regulated membrane fusion in vitro and in cells. Together, these findings reveal further convergence of reconstituted and cell-based systems.

Source: The Journal of Cell Biology

DOI: 10.1083/jcb.201104079

Authors: Zhao Wang, Huisheng Liu, Yiwen Gu, Edwin R. Chapman

Institutions: Howard Hughes Medical Institute, University of Wisconsin–Madison

Language: English

Topic: Cellular transport and secretion

Subfield: Cell Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: hybrid

Funders: Howard Hughes Medical Institute, National Institute of Mental Health

Award: Synaptotagmin C2B Domain as a Ca2+ Sensing Module