Vac14 protein multimerization is a prerequisite step for Fab1 protein complex assembly and function.

摘要: Phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2) helps control various endolysosome functions including organelle morphology, membrane recycling, and ion transport. Further highlighting its importance, PtdIns(3,5)P2 misregulation leads to the development of neurodegenerative diseases like Charcot-Marie-Tooth disease. The Fab1/PIKfyve lipid kinase phosphorylates PtdIns(3)P into whereas Fig4/Sac3 phosphatase antagonizes this reaction. Interestingly, Fab1 Fig4 form a common protein complex that coordinates synthesis degradation by poorly understood process. Assembly requires Vac14/ArPIKfyve, multimeric scaffolding adaptor turnover PtdIns(3,5)P2. However, properties function Vac14 multimerization remain mostly uncharacterized. Here we identify several conserved C-terminal motifs on required for self-interaction provide evidence likely forms dimer. We also show monomeric mutants do not support interaction with or Fig4, suggesting is first molecular event in assembly complex. Finally, cells expressing have enlarged vacuoles fragment after hyperosmotic shock, which indicates levels are greatly abated. Therefore, our observations an essential role homocomplex controlling levels.