Studies on the fusion of viral coat proteins with the cell plasma membrane have suggested a "hairpin" conformation of viral and membrane proteins, leading to the formation of a fusion pore (Chan and Kim, 1998
). Analogous to viral fusion, it has been previously hypothesized (Jeong et al., 1998) that molecular assembly of SNAREs in a certain conformation in opposing bilayers, leads to t-/v-SNARE coiling and supercoiling and membrane fusion. In the present study, we demonstrate that, when opposing bilayers meet, SNAREs arrange in a ring pattern resulting in the formation of a conducting pore. The next step is to understand the regulation and disassembly of such pores. SNAREs are known to form very stable complexes. Even at 90°C (Fasshaurer et al., 1997) or with sodium dodecyl sulfate treatment (Hayashi et al., 1995), t-/v-SNARE complexes are stable. The soluble N-ethylmaleimide-sensitive factor NSF, an ATPase involved in disassembly of SNARE complexes (Söllner et al., 1993a), will be a candidate protein to be used in subsequent studies.
ACKNOWLEDGMENTS
We thank Drs. James E. Rothman and Thomas H. Söllner, Memorial Sloan Kettering Cancer Center, for their generous gift of purified recombinant SNARE proteins.
This work is supported by National Institutes of Health grants DK56212, and NS39918 to B.P.J. and National Institutes of Health Fellowship DK60368 to S.J.C.
FOOTNOTES
Address reprint requests to Bhanu P. Jena, Ph.D., Professor, Department's of Physiology and Pharmacology, Wayne State University School of Medicine, 5239 Gordon Scott Hall, 540E Canfield Ave., Detroit, MI 48201-1928. Tel.: 313-577-1532; Fax: 313-993-4177; E-mail: bjena@med.wayne.edu
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Submitted August 2, 2002 and accepted for publication August 22, 2002.
Sang-Joon Cho and Marie Kelly contributed equally to this paper.
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