Allosteric regulation of the Golgi-localized PPM1H phosphatase by Rab GTPases modulates LRRK2 substrate dephosphorylation in Parkinson’s disease
Published August 25, 2025
Output Details
Preprint May 19, 2025
Published August 25, 2025
Description
PM1H phosphatase reverses Parkinson’s disease-associated, Leucine Rich Repeat Kinase 2-mediated, Rab GTPase phosphorylation. We showed previously that PPM1H relies on an N-terminal amphipathic helix for Golgi membrane localization and this helix enables PPM1H to associate with liposomes *in vitro*; binding to highly curved liposomes activates PPM1H’s phosphatase activity. We show here that PPM1H also contains an allosteric binding site for its non-phosphorylated reaction products, Rab8A and Rab10. Microscale thermophoresis revealed that PPM1H binds thio-phosphorylated Rab8A at the active site with a KD of ∼1μM; binding of Rab8A and Rab10 to an alternative site is of similar affinity and is not detected for another LRRK2 substrate, Rab12. Non-phosphorylated Rab8A or Rab10 inhibit PPM1H phosphatase reactions at concentrations consistent with their measured binding affinities and fail to inhibit PPM1H L66R phosphatase reactions. Independent confirmation of non-phosphorylated Rab binding to PPM1H was obtained by sucrose gradient co-flotation of non-phosphorylated Rabs with liposome-bound PPM1H. Finally, Rab8A or Rab10 binding also requires PPM1H’s amphipathic helix, without which the interaction affinity is decreased about 6-fold. These experiments indicate that Golgi associated Rab proteins contribute to the localization of PPM1H and non-phosphorylated Rabs regulate PPM1H phosphatase activity via an allosteric site. Targeting this site could represent a strategy to enhance PPM1H-mediated dephosphorylation of LRRK2 substrates, offering a potential therapeutic approach to counteract LRRK2-driven Parkinson’s disease.
Identifier (DOI)
10.1016/j.jbc.2025.110679
