INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
"Cyclin- related protein kinases (CRKs) and putative partners in the cell-cycle control of T. cruzi"
Autor/es:
TÉLLEZ-IÑÓN MA. TERESA
Lugar:
Antofagasta
Reunión:
Congreso; I Congreso Chileno de Parasitología,; 2008
Institución organizadora:
Soc. Parasitología Chile
Resumen:
Trypanosoma cruzi CRKs and partners in the cell cycle" Téllez-Iñón Ma. Teresa. INGEBI-CONICET. Vta. de Obligado 2490, 2nd. floor (1428) Buenos Aires, Argentina. Email: mtellez@dna.uba.ar In Trypanosoma cruzi two CRKs genes TcCRK1 and TcCRK3 have been cloned. TcCRK1 levels and localization do not vary during the cell cycle, being highly concentrated in the kinetoplast, suggesting a putative function in this organelle. TzCRK3 expression and activity was present throughout three life cycle stages of the parasite. In synchronized epimastigotes with hydroxyurea, TzCRK3 activity peaked at G2/M boundary while the kinase associated to p13suc1-beads increased at the same time point remaining high until late G2/M. TzCRK3 expression was constant during the cell cycle showing the common pattern of CDK regulation. The results allow us to postulate that CRK3 shares functional homology with CDK1, and that it has a role controlling the G2/M transition in T. cruzi . The activity of CDKs is regulated by multiple regulatory mechanisms. At least four distinct posttranslational mechanisms positively regulated CDKs function, including binding of cyclins, binding of p13 (CKS) proteins phosphorylation and dephosphorylation of the protein by specific kinases and phosphatases. Searching proteins that regulate the cdc2-activity, we identified Tcp12CKS1 a member of the CKS family in the parasite T. cruzi, similar to the Leishmania p12 (Mottram, 1996). TcCKS1 is expressed in the three forms of T. cruzi. Anti-Tcp12CKS1 antiserum, immunoprecipitate protein kinase activities that varies depending on the stage analyzed, and thus suggesting that different stages have different CKS-CRK complexes. Immunoprecipitation and Western blot analyses demonstrated that in the epimastigote stage, p12CKS1 stably interacts with TcCRK1 and TcCRK3. In addition, Tcp12CKS1 was able to rescue the p13SUC1 null mutant of S. pombe. The functional complementation between the CKS proteins of two evolutionary distant organisms supports the role of Tcp12CKS1 as a key regulator in T. cruzi cell cycle. Studies in multiple systems have suggested that PIN-1 is a protein that plays a critical role for mitosis progression in mammalian cells and yeast. PIN1 participate in the phosphorylation-dependent prolyl isomerase that changes the conformation of its substrates controlling cell-cycle progression. We identified TcPIN1 in T.cruzi as a homologue of the essential hPin1 parvulin PPIase. Based on functional assays, subcellular localization and preliminary enzymatic PPIase activity, we showed that TcPIN1 is a member of the Pin1-type PPIases, suggesting the existence of an additional conserved level of post-translational control in trypanosomatids. As all plants homologues identified, TcPin1 have not WW domain at the N-terminus or analogous module. Nevertheless, TcPin1 is able to rescue the temperature sensitive phenotype of a mutation in the hPin1 homologue ESS1/PTF1 in S. cerevisiae. On the basis of functional assay and enzymatic PPIase activity we demonstrated that TcPin1 is a member of the Pin1-type PPIases, suggesting the existence of an additional conserved level of post-translational control in trypanosomatids. Supported by FONCYT, CONICET, UBA.