LEISHMANIA-DONOVANI HEAT-SHOCK-PROTEIN-100 - CHARACTERIZATION AND FUNCTION IN AMASTIGOTE STAGE DIFFERENTIATION

We report the cloning and molecular analysis of the Leishmania donovan i clpB gene. The protein-coding region is highly conserved compared wi th its L. major homologue, while 5'-and 3'-flanking DNA sequences disp lay considerable divergence, The encoded mRNA has an unusually long 5' -leader sequence typical for RNAs, which are translated preferentially under heat stress. The gene product, a 100-kDa heat shock protein, Hs p100, becomes abundant only during sustained heat stress, but not unde r common chemical stresses, Hsp100 associates into trimeric complexes and is found mostly in a cytoplasmic, possibly membrane-associated loc alization as deter mined by immune electron microscopy. Hsp100 shows i mmediate early expression kinetics during axenic amastigote developmen t, In its absence, expression of at least one amastigote stage-specifi c protein family is impaired.