4wnr

Publication Abstract from PubMed

Mutations in leucine-rich-repeat kinase 2 (LRRK2) are the most frequent cause of late-onset Parkinson's disease (PD). LRRK2 belongs to the Roco family of proteins which share a conserved Ras-like G domain (Roc) and a C-terminal of Roc domain (COR) tandem. The nucleotide state of small G proteins is strictly controlled by Guanine nucleotide Exchange Factors (GEFs) and GTPase activating proteins (GAPs). Because of contradictory structural and biochemical data, the regulatory mechanism of the LRRK2 Roc G-domain and the RocCOR tandem is still under debate. Here we present the first nucleotide bound Roc structure and used LRRK2 and bacterial Roco proteins to characterize the RocCOR function in more detail. Nucleotide binding induces a drastic structural change in the Roc-COR domain interface, a region strongly implicated in LRRK2 patient mutations. Our data confirm previous assumptions that the C-terminal sub-domain of COR functions as a dimerization device. We show that dimer formation is independent of nucleotide. The affinity for GDP/GTP is in the micromolar range, the results of which are fast dissociation rates in the s-1 range. Thus, Roco proteins are unlikely in need of GEFs to achieve activation. Monomeric LRRK2 and Roco G-domains have a similar low GTPase activity as small G proteins. We show that GTPase activity in bacterial Roco is stimulated by nucleotide dependent dimerization of the G-domain within the complex. We thus propose that Roco proteins don't require GAPs to stimulate GTP hydrolysis but stimulate each other by one monomer completing the catalytic machinery of the other.

Revisiting the Roco G protein cycle.,Terheyden S, Ho FY, Gilsbach BK, Wittinghofer A, Kortholt A Biochem J. 2014 Oct 15. PMID:25317655^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.