Targeting of the Arf-GEF GBF1 to lipid droplets and Golgi membranes.
Lipid droplet metabolism and secretory pathway trafficking both require activation of the Arf1 small G protein. The spatiotemporal regulation of Arf1 activation is mediated by guanine nucleotide exchange factors (GEFs) of the GBF and BIG families, but the mechanisms of their localization to multiple sites within cells are poorly understood. Here we show that GBF1 has a lipid-binding domain (HDS1) immediately downstream of the catalytic Sec7 domain, which mediates association with both lipid droplets and Golgi membranes in cells, and with bilayer liposomes and artificial droplets in vitro. An amphipathic helix within HDS1 is necessary and sufficient for lipid binding, both in vitro and in cells. The HDS1 domain of GBF1 is stably associated with lipid droplets in cells, and the catalytic Sec7 domain inhibits this potent lipid-droplet-binding capacity. Additional sequences upstream of the Sec7 domain-HDS1 tandem are required for localization to Golgi membranes. This mechanism provides insight into crosstalk between lipid droplet function and secretory trafficking.
Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France.
Samuel
S
Bouvet
Marie-Pierre
MP
Golinelli-Cohen
Vincent
V
Contremoulins
Catherine L
CL
Jackson
D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D002479:Inclusion Bodies / Q000235:genetics / Q000378:metabolism*; D050356:Lipid Metabolism; D010957:Plasmids; D021381:Protein Transport; D055571:Secretory Pathway; D014162:Transfection
D020662:Guanine Nucleotide Exchange Factors; D020823:ADP-Ribosylation Factor 1
Amphipathic helix; Arf1 small G protein; Golgi; Guanine nucleotide exchange factor (GEF); Lipid binding domain; Lipid droplet