Work

Quantitative characterization of PP2A-derived peptides modulating the LRRK2:PP2A protein-protein interaction

Year: 2026

Type: preprint

Abstract: Parkinson's disease (PD) is the most prevalent motor neurodegenerative disorder with currently no disease-modifying treatment. LRRK2 is a major PD genetic determinant, showing dephosphorylation of its heterologous phosphorylation sites (S910/S935) in disease. We previously proposed preventing LRRK2 S910/S935 dephosphorylation as a PD therapeutic approach attenuating LRRK2 hyperactivation. As PP2A phosphatase subunits are key regulators of this dephosphorylation, we targeted the LRRK2:PP2A protein-protein interaction (PPI) as strategy to prevent LRRK2 dephosphorylation. Using Microscale Thermophoresis, we measured the binding affinities of two PPP2CA-derived peptides, HT16 and QA16, for LRRK2, with dissociation constants ranging from 0.3 to 5 µM. Strikingly, co-incubation of both peptides showed a sevenfold improved binding affinity, suggesting two distinct but allosterically coupled binding sites on LRRK2. Co-immunoprecipitation experiments in HEK293T cells further demonstrated that these peptides compete with PPP2CA for binding to LRRK2. AlphaFold2 structural modelling identified putative PPP2CA residues at the LRRK2 interaction interface. Alanine scanning of these residues clarified their contribution to the interaction pointing to Y130, D223 and H230 of PPP2CA as potential LRRK2 binding hotspots. These results provide the first quantitative characterization of the LRRK2:PPP2CA interaction interface and establish peptide molecular tools to develop selective PPI modulators blocking LRRK2 S910/S935 dephosphorylation as PD therapeutic approach.

Source: Research Square

DOI: 10.21203/rs.3.rs-11204417/v1