The PIKfyve-VAC14-FIG4 complex synthesizes and turns over PI(3,5)P₂, an essential signaling lipid. A medium-resolution structure revealed that VAC14 forms a star-shaped pentamer scaffold. Two legs of VAC14 bind FIG4, with one leg also occupied by PIKfyve. The significance of VAC14 oligomerization was unknown. Here, using Alphafold2 and cryo-EM maps we generated an atomic-resolution prediction, and found that some mutations linked to pediatric neurodegenerative diseases reside in the VAC14-VAC14 interfaces. A corresponding yeast mutation, along with additional mutations, demonstrate that VAC14 oligomerization is critical for Fab1/PIKfyve function. These mutations cause defects in the generation of PI(3,5)P₂, in VAC14 localization, and in VAC14 oligomerization. Similarly, VAC14 patient mutations expressed in human VAC14 knock-out cells, are defective in the formation of the PIKfyve-VAC14-FIG4 complex, as measured by pull-down assays, are defective in VAC14 oligomerization as measured by fluorescence-detection size exclusion chromatography of cell lysates and are defective in co-localization with VPS35-containing endosomes. These studies show that VAC14 oligomerization plays a crucial role in the regulation of PIKfyve/FAB1 and provide insights into selected patient mutations. Moreover, they suggest that small molecules that stabilize the VAC14 complex may provide an intervention for diseases linked to mutations in VAC14.

• PMID: 40305106
• DOI full text
• PubMed
• PubTator

Reference Type

Journal Article

Authors

Zhang L, Uygun T, Hahn HJ, Liu Y, Rivero-Ríos P, Li D, Navratna V, Bristow E, Luo G, Kovarzin A, ... Show all

Primary Lit For

Additional Lit For

Review For