SNARE assembly and membrane fusion, a kinetic analysis.
SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) assembly may promote intracellular membrane fusion, an essential process for vesicular transport in cells. Core complex formation between vesicle-associated SNARE and target membrane SNARE perhaps drives the merging of two membranes into a single bilayer. Using spin-labeling EPR, trans-SNARE complex formation was monitored "locally" at four different core locations of recombinant yeast SNAREs, which are individually reconstituted into phospholipid vesicles. The results indicate that the time scales of core formation are virtually the same at all four locations throughout the core region, indicating the possibility of a single step core assembly, which appears to be somewhat different from what has been postulated by the "zipper" model. The EPR data were then compared with the kinetics of the lipid mixing measured with the fluorescence assay. The analysis suggests that SNARE core assembly occurs on a much faster time scale than the lipid mixing, providing a new insight into the timing of individual events in SNARE-induced membrane fusion.
Zhang
Fan
F
Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA.
Chen
Yong
Y
Su
Zengliu
Z
Shin
Yeon-Kyun
YK
D002462:Cell Membrane / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D003902:Detergents / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D007700:Kinetics; D008051:Lipid Bilayers / Q000378:metabolism*; D008055:Lipids / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D017830:Octoxynol / Q000494:pharmacology; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D050600:SNARE Proteins; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D033921:Vesicular Transport Proteins / Q000737:chemistry*
D003902:Detergents; D005656:Fungal Proteins; D008051:Lipid Bilayers; D008055:Lipids; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D050600:SNARE Proteins; D033921:Vesicular Transport Proteins; D017830:Octoxynol; D004247:DNA; D005982:Glutathione Transferase; D003545:Cysteine