Heat shock protein 100 and the amastigote stage-specific A2 proteins of Leishmania donovani

HSP100 protein in Leishmania spp. plays an important role for the survival and integrity of intracellular amastigotes. The A2 proteins of L. donovani are functionally linked to HSP100. There is evidence for an interdependence between these two proteins, which are both expressed predominantly in the amastigote stage of Leishmania donovani. Mutant strains lacking either of these proteins display very similar phenotypes, i.e. loss of virulence both in vivo and in vitro. Also, both proteins colocalise specifically to small foci within the cytoplasm of amastigotes.

Expression and subcellular localization of cpn60 protein family members in Leishmania donovani

We have identified two diverged members of the cpn60 gene family in Leishmania donovani, causative agent of Indian Kala Azar. One of the genes, cpn60.1, although actively transcribed, is not expressed to detectable levels of protein in cultured L. donovani. The other gene, cpn60.2, which, compared with cpn60.1, shows a higher sequence conservation with the hsp60 genes from Trypanosoma brucei and Trypanosoma cruzi is expressed constitutively in cultured promastigotes. The abundance of the gene product, Cpn60.2, increases by 2.5-fold under heat stress and in axenic amastigotes of L. donovani. Cpn60.2 is also found enriched in mitochondrial cell fractions and localizes to the mitochondrial matrix. We conclude that Cpn60.2 is the major mitochondrial chaperonin in Leishmania.