Interactions between P1 and P2 proteins from Trypanosoma cruzi

MAXIMILIANO JURI AYUB; MARTÍN EDREIRA; CARLOS AGUILAR; MARIANO LEVIN

Villa Carlos Paz, Córdoba, Argentina

Congreso; XXXVIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2002

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The large subunit of all ribosomes possesses a long protruding stalk, which consists of several copies of the acidic P proteins. In Trypanosoma cruzi these proteins are TcP0, TcP1, TcP2a and TcP2b. The P proteins present a C-terminal conserved sequence, which is a major epitope specifically recognized by sera from patients with Chagas disease. In the present work, we expressed and tested interactions among the P proteins. Western blot using specific mAbs confirmed the identity of these proteins. Electrophoresis under native conditions showed a strong interaction between P1 and P2b. When the complex P1/P2b was subject to two dimension electrophoresis, we observed that P1 and P2b co-migrate under nondenaturing conditions, but were separated in the presence of SDS, showing the non covalent nature of the interaction. These results were confirmed by immunoblotting using different mAbs. Urea gradient electrophoresis showed that P1 and P2b did not present tertiary structure or tendency to homodimerization. In addition, the dissociation of the complex P1/P2b was evident as the urea concentration increased. We confirmed the interaction between P1 and P2b under physiological conditions using two hybrid. These assays also evidenced a very weak interaction between P1 and P2a, that was not detected by the other methods.