EXPRESSION AND LOCALIZATION OF TRYPANOSOMA-CRUZI HSP60

A 60-kDa heat shock protein (hsp60) is involved in mitochondrial prote in folding and assembly of oligomeric protein complexes in the mitocho ndrial matrix. Here we report the isolation of Trypanosoma cruzi hsp60 cDNAs, the determination of the organization and chromosomal location of the genes, and the assessment of the heat-regulated expression and subcellular location of the protein. T. cruzi hsp60 is encoded by a m ultigene family organized in two allelic direct tandem arrays on a chr omosome of 1.6 Mb. The regulation of hsp60 expression by heat is compl ex. While the hsp60 mRNA level is 6-fold higher at 37 degrees C than a t either 26 degrees C or 42 degrees C, the hsp60 protein level remains essentially constant across all temperatures examined. Further analys is of the protein by two-dimensional immunoblotting revealed the exist ence of multiple isoforms that, with increasing temperature, shift in relative abundance from the more basic to the more acidic. A combinati on of immunofluorescence microscopy and cell fractionation was used to show that hsp60 is distributed throughout the matrix of the mitochond rion - a location distinct from that of the 70-kDa mitochondrial hsp, mtp70, which is associated with the kinetoplast.