Figure 5. Proposed mechanism of action of Nb_Roco1.

CtRoco is shown schematically with the Roc domains in red, COR domains in blue and LRR domains in yellow. Upon GTP binding CtRoco undergoes a dimer to monomer transition in addition to intra-subunit conformational changes [36,37]. After GTP hydrolysis CtRoco re-dimerizes. Nb_Roco1, indicated in gray, binds to an epitope on the RocCOR domain that changes conformation between the dimeric and monomeric states, with the highest affinity for the monomeric state. Through binding, Nb_Roco1 changes the dimer–monomer equilibrium towards the monomer, thus counteracting the effect of the PD-analogous L487A mutant.