Arginine deiminase sumoylation: a novel post-translational modification in Giardia lamblia

VRANYCH CV; RIVERO MR; TOUZ MC; ROPOLO AS

Villa Carlos Paz

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The protozoan parasite Giardia lamblia utilizes arginine deiminase (gADI) to produce energy from L-arginine under anaerobic conditions, a pathway restricted to prokaryotic organisms. Recently, analyzing the protein expression of gADI we found several bands including a major 85 kDa band instead of the predicted 64 kDa, that indicates a possible post-translational modification. Phosphorylation was predicted in several positions as well as a high probability of modification by the 11kDa SUMO-1 protein (small ubiquitin-related modifier protein). Immunoblotting experiments using anti-SUMO mAb detected an 85 kDa protein that corresponds to the gADI higher band. The ability of anti-SUMO mAb to immunoprecipitate the 85 kDa band of gADI confirmed the gADI-SUMO interaction. A predicted function of sumoylation of proteins is the cytoplasm/nuclei translocation, and we found that during differentiation of the parasite mainly the 85 kDa form of gADI translocate to the nucleus, inducing the downregulation of the encystation process. Further research into the possibility that gADI function could be regulated by sumoylation may provide insight into the biology of this important intestinal parasite and also contribute to the understanding of the evolution of protein modification in eukaryotic cells.