Based on a previous high-throughput yeast two-hybrid (Y2H) screen of the Brucella melitensis ORFeome to identify bacterial proteins interacting with human putatively phagosomal proteins, the human Rab2 GTPase was detected interacting with a B. melitensis protein named RicA (Rab2 interacting conserved protein A). In silico analysis predict RicA protein to be 175 aa long, conserved in many bacteria group and possess features of a putative acetyltransferase. RicA was further characterized in this thesis. Analyses in Y2H of randomly mutated alleles of ricA coding sequence indicate three regions are free of mutations, which is expected for the interaction interface. One of them contains a small segment that was called IGFP (Ile-Gly-Phe-Pro) loop. The IGFP loop was mutagenized at the Ile and Phe positions of this loop, and most of the mutants generated loss of interaction, suggesting that RicA interacts with Rab2 through the IGFP loop. Rab2 3D structure analysis revealed two complementary hydrophobic patches which interestingly correspond to switch I and switch II regions, that are conformationally modified by GTP binding. This is consistent with apparently preferential binding of RicA to GDP bound form of GST-Rab2.
Identification and characterization of the interaction between human Rab2 GTPase and Brucella spp. RicA protein.
Nkengfac, B. (Author). 16 Dec 2009
Student thesis: Doc types › Doctor of Sciences