NEW INSIGHTS INTO THE INTERACTION MAP OF TRYPANOSOMA CRUZI RIBOSOMAL P PROTEIN COMPLEX

SMULSKI CR; LONGHI SA; JURI AYUB M; SIMONETTI L; BASILE JN; HOEBEKE J; LEVIN MJ

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunion Anual Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2007

The large subunit of the eukaryotic ribosome possesses a long andprotruding stalk formed by the ribosomal P proteins. It is involvedin the translation step of protein synthesis through interaction withelongation factor 2 (EF2). The stalk, in T.cruzi, is composed by fourproteins of about 11 KDa, TcPla, TcPlb, TcP2a, TcP2b and a fifthTcP0 of about 30 KDa. A yeast two-hybrid based proteininteraction map was generated that indicated a central role forTcP0. Using Surface Plasmon Resonance the kinetics of each of thepossible interactions between the members of this protein familywas tested. The assembly of temary complexes was also assessed.TcP0 and TcP2b proteins were able to form homo dimers and alsointeracted with both Pl and both P2 proteins. The interactiondomains of TcP0 and TcP2b were mapped using truncated proteinsand synthetic peptides, respectively. All proteins, with theexception of TcP2a, interact with the EF2 but the small proteinsshowed a stronger affinity than TcP0. The C-terminal region ofTcP2b (peptide R13) seems to be involved in the interaction withEF2, since R13 was able to inhibit the second part of the associationphase. Other regions of the protein may also be involved, becauseR13 had no effect on the first step of the association phase.Compared to other species, T. cruzi clearly displays a specificpattern of ribosomal P protein interactions.