Identification and characterization of an hPar14 homolog in Trypanosoma cruzi

ERBEN E, VALGUARNERA PE, MT TÉLLEZ-IÑÓN.

Mar del Plata, Buenos Aires

Congreso; XLIII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB).; 2007

SAIB

A second member of the parvulin family of peptidyl prolyl cis/trans isomerases was identified in Trypanosoma cruzi. A database search was performed to screen for additional parvulin homologous genes in the GeneDB trypanosomatid database. The encoding region of the gene consists of 375 bp and encodes a protein of 124 amino acids. The TcPar14 gene was expressed and purified as described for TcPIN1 (Erben et al., 2007). The PPIase-activity of TcPar14 was investigated using the protease-free method. Using the substrate Suc-Ala-Arg-Pro-Phe-NH-Np, a specificity constant kcat/KM of 194 /mM/s was found for TcPar14. This is about 50- fold higher than the respective value of kcat/KM for human Par14. A comparison of the relative specificity constants for various substrates shows a strong preference for a substrate with the basic arginine residue preceding proline. The analysis of the sequence of TcPar14 showed the existence of the sequence motifs typical of the parvulin catalytic core. Like most hPar14 homolog parvulins, TcPar14 has an N-terminal extension but in contrast to hPin1, a WW domain for protein/protein interactions motif could not be identified.