Intracellular Vesicle Fusion Requires a Membrane-Destabilizing Peptide Located at the Juxtamembrane Region of the v-SNARE

Rathore, Shailendra S.; Liu, Yinghui; Yu, Haijia; Wan, Chun; Lee, MyeongSeon; Yin, Qian; Stowell, Michael H.B.; Shen, Jingshi

We reasoned that, if the juxtamembrane motif of VAMP2 promotes membrane fusion by destabilizing the lipid bilayer, then it could be functionally substituted with an unrelated peptide known to disrupt the membrane structure. To test this possibility, the VAMP2 juxtamembrane motif was replaced with the TatP59W peptide, a variant of the Tat peptide derived from the Tat protein of human immunodeficiency virus-1 (HIV-1) (Thorén et al., 2005) . Like the VAMP2 juxtamembrane motif, the TatP59W peptide is a short membraneembedded stretch comprised of both basic and hydrophobic residues ( Figure 6A ; Thorén et al., 2005) . Importantly, the TatP59W peptide exhibits no sequence similarity with the juxtamembrane motif of VAMP2 and is not involved in exocytosis ( Figure 6A ; Thorén et al., 2005) . We observed that, although mutations of the juxtamembrane motif abolished SNARE-Munc18-1 mediated liposome fusion, the fusion was restored when the TatP59W peptide was introduced into the juxtamembrane region of VAMP2 ( Figure 6B ). Thus, the juxtamembrane motif of VAMP2 can be replaced by an unrelated bilayer-disrupting peptide in the membrane fusion reaction, further demonstrating that the juxtamembrane motif promotes membrane fusion by destabilizing the lipid bilayer.