A feed-forward pathway drives LRRK2 kinase membrane recruitment and apparent activation

Activating mutations in the Leucine Rich Repeat Kinase 2 (LRRK2) cause Parkinson’s disease and activated LRRK2 phosphorylates a subset of Rab GTPases. Moreover, Golgi-associated Rab29 can recruit LRRK2 to the surface of the Golgi and activate it there for both auto- and Rab substrate phosphorylation. Here we define the precise Rab29 binding region of the LRRK2 Armadillo domain between residues 360-450 and show that this site, termed “Site #1”, can also bind additional LRRK2 substrates, Rab8A and Rab10. Moreover, we identify a distinct, N-terminal, higher affinity interaction interface between LRRK2 phosphorylated Rab8 and Rab10 termed “Site #2”, that can retain LRRK2 on membranes in cells to catalyze multiple, subsequent phosphorylation events. Kinase inhibitor washout experiments and mutation analysis demonstrate that rapid recovery of kinase activity in cells depends on the ability of LRRK2 to associate with phosphorylated Rab reaction products. Reconstitution of purified LRRK2 recrui...