5 kDa. The deduced amino acid sequence of the protein encoded by the TcKAP4 gene includes 28% basic residues,

with a predicted pI of 14.5. The TcKAP6 gene is 558 base pairs long and encodes a polypeptide with a predicted molecular MK-8776 cost weight of 21.2 kDa. The amino acid sequence of TcKAP6 includes 30% of basic residues and this protein has a predicted pI of 11.3. The amino acid sequence data reported here are available from GenBank under the accession numbers ABR15473 for TcKAP4 and ABR15474 for TcKAP6. Both TcKAP4 and TcKAP6 have a S3I-201 molecular weight clearly identifiable cleavable presequence in the N-terminal region similar to that described for the KAPs of C. fasciculata and potentially involved in mitochondrial import (figure 2). These presequences are absent from the mature forms of the proteins in C. fasciculata and with the exception of their length, have all the properties usually associated with cleavable mitochondrial

presequences [12–14]. Similar sequences have been identified in the C. fasciculata kinetoplast DNA polymerase beta, T. brucei hsp60 and Leishmania tarentolae aldehyde dehydrogenase [38–40]. Figure 2 Comparison of N-terminal sequences of KAPs from C. fasciculata and T. cruzi. The presequences predicted to be involved in kinetoplast import are shown in bold type. The boxes indicate the highly conserved amino acids. Note that all sequences begin with the sequence M, L, R. In all sequences other than those of CfKAP4 and TcKAP4, the fifth amino acid is hydroxylated and the ninth is generally hydrophobic. CfKAP4 (PIR JC6092), CfKAP3 (GenBank accession number AY143553), CfKAP2 (GenBank accession numbers AF008943 and AF008944) and CfKAP1 (GenBank Smad inhibitor accession number AF034951) are KAPs from C. fasciculata whereas TcKAP4 (GenBank accession number ABR15473) and TcKAP6 (GenBank accession number ABR15474) are T. cruzi KAPs. As reported for their counterparts in C. fasciculata [12, 13], the TcKAPs are positively charged and small, consistent with a role in DNA charge neutralization and kDNA condensation in T. cruzi. The interaction between KAPs and kDNA may involve nonspecific electrostatic binding to DNA, interaction with specific regions

of the minicircles or both types of association. However, further studies are required to investigate the occurrence of interaction between TcKAPs and kDNA, and how these DAPT molecular weight interactions determine DNA network organization in T. cruzi. Detection of TcKAPs in the distinct developmental stages of T. cruzi After cloning and expression, recombinant TcKap4 and TcKap6 proteins (figure 3) were purified in order to produce mouse polyclonal antisera against them. These antisera were used in immunoblotting assays, to analyze the expression of TCKAPs in proliferative and non proliferative stages of T. cuzi. Cell extracts of epimastigotes, amastigotes/intermediate forms and trypomastigotes were used and both antisera were able to detect a single polypeptide in all developmental stages of T. cruzi.