SNAREs in opposing bilayers interact in a circular array to form conducting pores.
The process of fusion at the nerve terminal is mediated via a specialized set of proteins in the synaptic vesicles and the presynaptic membrane. Three soluble N-ethylmaleimide-sensitive factor (NSF)-attachment protein receptors (SNAREs) have been implicated in membrane fusion. The structure and arrangement of these SNAREs associated with lipid bilayers were examined using atomic force microscopy. A bilayer electrophysiological setup allowed for measurements of membrane conductance and capacitance. Here we demonstrate that the interaction of these proteins to form a fusion pore is dependent on the presence of t-SNAREs and v-SNARE in opposing bilayers. Addition of purified recombinant v-SNARE to a t-SNARE-reconstituted lipid membrane increased only the size of the globular t-SNARE oligomer without influencing the electrical properties of the membrane. However when t-SNARE vesicles were added to a v-SNARE membrane, SNAREs assembles in a ring pattern and a stepwise increase in capacitance, and increase in conductance were observed. Thus, t- and v-SNAREs are required to reside in opposing bilayers to allow appropriate t-/v-SNARE interactions leading to membrane fusion.
Cho
Sang-Joon
SJ
Departments of Physiology and Pharmacology, Wayne State University School of Medicine, 540E Canfield Avenue, Detroit, MI 48201, USA.
Kelly
Marie
M
Rognlien
Katherine T
KT
Cho
Jin Ah
JA
Hörber
J K Heinrich
JK
Jena
Bhanu P
BP
D000538:Aluminum Silicates / Q000737:chemistry*; D055592:Biophysical Phenomena; D001703:Biophysics; D002462:Cell Membrane / Q000378:metabolism; D004594:Electrophysiology; D008051:Lipid Bilayers / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry; D050600:SNARE Proteins; D013997:Time Factors; D033921:Vesicular Transport Proteins
D000538:Aluminum Silicates; D008051:Lipid Bilayers; D008565:Membrane Proteins; D008567:Membranes, Artificial; D011994:Recombinant Proteins; D050600:SNARE Proteins; D033921:Vesicular Transport Proteins; C011934:mica