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  • A structure of substrate-bound Synaptojanin1 provides new insights in its mechanism and the effect of disease mutations.

A structure of substrate-bound Synaptojanin1 provides new insights in its mechanism and the effect of disease mutations.

eLife (2020-12-23)
Jone Paesmans, Ella Martin, Babette Deckers, Marjolijn Berghmans, Ritika Sethi, Yannick Loeys, Els Pardon, Jan Steyaert, Patrik Verstreken, Christian Galicia, Wim Versées
ABSTRACT

Synaptojanin1 (Synj1) is a phosphoinositide phosphatase, important in clathrin uncoating during endocytosis of presynaptic vesicles. It was identified as a potential drug target for Alzheimer's disease, Down syndrome, and TBC1D24-associated epilepsy, while also loss-of-function mutations in Synj1 are associated with epilepsy and Parkinson's disease. Despite its involvement in a range of disorders, structural, and detailed mechanistic information regarding the enzyme is lacking. Here, we report the crystal structure of the 5-phosphatase domain of Synj1. Moreover, we also present a structure of this domain bound to the substrate diC8-PI(3,4,5)P3, providing the first image of a 5-phosphatase with a trapped substrate in its active site. Together with an analysis of the contribution of the different inositide phosphate groups to catalysis, these structures provide new insights in the Synj1 mechanism. Finally, we analysed the effect of three clinical missense mutations (Y793C, R800C, Y849C) on catalysis, unveiling the molecular mechanisms underlying Synj1-associated disease.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
D-myo-Inositol 1,2,3,4,5,6-Hexakisphosphate, Dodecasodium Salt, Zea mays, Major phosphorus compound in plants that chelates with a variety of di- and trivalent cations.
Sigma-Aldrich
p-Nitrophenyl Phosphate Liquid Substrate System, liquid
Sigma-Aldrich
D-myo-Inositol 1,4,5-Trisphosphate, Trisodium Salt, Sodium salt of D-Ins(1,4,5)P₃ that has similar biological properties as the lithium salt.