Unravelling and modulating the complex conformational cycle of the Roco protein family

Roco proteins form a unique class of multi-domain GTPases, often also bearing kinase activity. Lately these proteins have moved into focus, since mutations in several human orthologues have been linked to disease. In particular, mutations in the gene coding for LRRK2 are the most frequent genetic cause of late onset Parkinson’s disease (PD), a devastating neurodegenerative disorder affecting 1-
2% of the population above age 65. However, the regulatory mechanisms of these proteins, and how they are affected by disease-causing mutations, remain largely unknown. We have recently shown that Roco proteins need to cycle between a dimeric and monomeric form to exert their function. In this project we will use a combination of structural and biophysical/biochemical methods to unravel the details of the GTPase cycle underlying the action and regulation of different Roco representatives. These novel insights could form the basis for a new paradigm for GTPase regulation, and will allow us to understand the effect of pathogenic mutations. Moreover, we will
generate and characterize Nanobodies and stapled peptides that bind and block the Roco proteins in a certain conformation and thus modulate the Roco cycle. These allosteric modulators of Roco activity will not only be used as exquisite tools to investigate the regulatory mechanisms underlying Roco function in vitro and in cells, but could also pave the way for the development of novel types of therapeutics.