Electron Microscopy Structure of Dimeric LRRK2 Reveals a Structural and Regulatory Role of the COR Domain

Missense mutations in leucine-rich repeat kinase 2 (LRRK2) constitute the most common genetic cause of Parkinson disease (PD). LRRK2 is a 286-kDa multidomain protein containing several protein-protein interaction domains, including armadillo, leucine-rich and ankyrin repeats, as well as a Ras Of Complex proteins GTPase (ROC) and a kinase joined by a C-terminal Of ROC (COR) domain. PD-linked mutations are clustered in the catalytic core of LRRK2 suggesting that altered GTPase and kinase activities may be implicated in pathogenesis. Biochemical experiments suggest LRRK2 kinase activity may be regulated by dimerization. Electron microscopy imaging and single-particle 3D reconstruction, at a resolution of 22 A, reveal that LRRK2 purified from mouse brain forms elliptical homodimers with each monomer having a concave lune shape. Dimerization occurs via a single two-fold rotation axis, in which the two monomers interact via two main interfaces. Details in the electron microscopy map provide insight into the domain organization of LRRK2. Docking of a prokaryotic ROC-COR homologous structure suggests LRRK2 dimerization may be mediated primarily by the COR domain. Immunoprecipitation experiments confirm the predicted COR-COR interaction. Furthermore, competition experiments showed the COR domain inhibits LRRK2 kinase activity in vitro. Our data reveal the COR domain to play a critical role at the dimerization interface and in the regulation of LRRK2 kinase activity.