RT Journal Article
SR Electronic
T1 Phosphoinositides and SNARE chaperones synergistically assemble and remodel SNARE complexes for membrane fusion
JF Proceedings of the National Academy of Sciences
JO Proc Natl Acad Sci USA
FD National Academy of Sciences
SP 16191
OP 16196
DO 10.1073/pnas.0908694106
VO 106
IS 38
A1 Mima, Joji
A1 Wickner, William
YR 2009
UL http://www.pnas.org/content/106/38/16191.abstract
AB Yeast vacuole fusion requires 4 SNAREs, 2 SNARE chaperone systems (Sec17p/Sec18p/ATP and the HOPS complex), and 2 phosphoinositides, phosphatidylinositol 3-phosphate [PI(3)P] and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. By reconstituting proteoliposomal fusion with purified components, we now show that phosphoinositides have 4 distinct roles: PI(3)P is recognized by the PX domain of the SNARE Vam7p; PI(3)P enhances the capacity of membrane-bound SNAREs to drive fusion in the absence of SNARE chaperones; either PI(3)P or PI(4,5)P2 can activate SNARE chaperones for the recruitment of Vam7p into fusion-competent SNARE complexes; and either PI(3)P or PI(4,5)P2 strikingly promotes synergistic SNARE complex remodeling by Sec17p/Sec18p/ATP and HOPS. This ternary synergy of phosphoinositides and 2 SNARE chaperone systems is required for rapid fusion.