Unconventional secretion of Pichia pastoris Acb1 is dependent on GRASP protein, peroxisomal functions, and autophagosome formation.
In contrast to the enormous advances made regarding mechanisms of conventional protein secretion, mechanistic insights into the unconventional secretion of proteins are lacking. Acyl coenzyme A (CoA)-binding protein (ACBP; AcbA in Dictyostelium discoideum), an unconventionally secreted protein, is dependent on Golgi reassembly and stacking protein (GRASP) for its secretion. We discovered, surprisingly, that the secretion, processing, and function of an AcbA-derived peptide, SDF-2, are conserved between the yeast Pichia pastoris and D. discoideum. We show that in yeast, the secretion of SDF-2-like activity is GRASP dependent, triggered by nitrogen starvation, and requires autophagy proteins as well as medium-chain fatty acyl CoA generated by peroxisomes. Additionally, a phospholipase D implicated in soluble N-ethyl-maleimide sensitive fusion protein attachment protein receptor-mediated vesicle fusion at the plasma membrane is necessary, but neither peroxisome turnover nor fusion between autophagosomes and the vacuole is essential. Moreover, yeast Acb1 and several proteins required for its secretion are necessary for sporulation in P. pastoris. Our findings implicate currently unknown, evolutionarily conserved pathways in unconventional secretion.
Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Ravi
R
Manjithaya
Christophe
C
Anjard
William F
WF
Loomis
Suresh
S
Subramani
D000214:Acyl Coenzyme A / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D001681:Biological Assay; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004023:Dictyostelium; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal / Q000235:genetics; D036341:Intercellular Signaling Peptides and Proteins; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008561:Membrane Fusion / Q000187:drug effects; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009584:Nitrogen / Q000172:deficiency; D010084:Oxidation-Reduction / Q000187:drug effects; D010455:Peptides / Q000378:metabolism; D020675:Peroxisomes / Q000187:drug effects / Q000378:metabolism*; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism*; D010843:Pichia / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology
D000214:Acyl Coenzyme A; D005656:Fungal Proteins; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; C484455:SDF-2 protein, Dictyostelium discoideum; D009584:Nitrogen; D020123:Sirolimus