Lysophospholipids Facilitate COPII Vesicle Formation.
Melero ADepartment of Biochemistry, University of Geneva, 1211 Geneva, Switzerland; Swiss National Centre for Competence in Research in Chemical Biology, 1211 Geneva, Switzerland.
Chiaruttini NDepartment of Biochemistry, University of Geneva, 1211 Geneva, Switzerland.
Karashima TDepartment of Bioresource Science and Technology, Hiroshima University, Hiroshima 739-8528, Japan.
Riezman IDepartment of Biochemistry, University of Geneva, 1211 Geneva, Switzerland.
Funato KDepartment of Bioresource Science and Technology, Hiroshima University, Hiroshima 739-8528, Japan.
Barlowe CDepartment of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755-3844, USA.
Riezman HDepartment of Biochemistry, University of Geneva, 1211 Geneva, Switzerland; Swiss National Centre for Competence in Research in Chemical Biology, 1211 Geneva, Switzerland. Electronic address: howard.riezman@unige.ch.
Roux ADepartment of Biochemistry, University of Geneva, 1211 Geneva, Switzerland; Swiss National Centre for Competence in Research in Chemical Biology, 1211 Geneva, Switzerland. Electronic address: aurelien.roux@unige.ch.
English
Coat protein complex II (COPII) proteins form vesicles from the endoplasmic reticulum to export cargo molecules to the Golgi apparatus. Among the many proteins involved in this process, Sec12 is a key regulator, functioning as the guanosine diphosphate (GDP) exchange factor for Sar1p, the small guanosine triphosphatase (GTPase) that initiates COPII assembly. Here we show that overexpression of phospholipase B3 in the thermosensitive sec12-4 mutant partially restores growth and protein transport at non-permissive temperatures. Lipidomics analyses of these cells show a higher content of lysophosphatidylinositol (lysoPI), consistent with the lipid specificity of PLB3. Furthermore, we show that lysoPI is specifically enriched in COPII vesicles isolated from in vitro budding assays. As these results suggested that lysophospholipids could facilitate budding under conditions of defective COPII coat dynamics, we reconstituted COPII binding onto giant liposomes with purified proteins and showed that lysoPI decreases membrane rigidity and enhances COPII recruitment to liposomes. Our results support a mechanical facilitation of COPII budding by lysophospholipids.