Characterization of mitochondria-located small heat shock protein from tomato (Lycopersicon esculentum)

We cloned and sequenced a full-length cDNA encoding the precursor of the mi tochondria-located small heart shock protein (MT-sHSP) gene (LeHSP23.8) fro m tomato (Lycopersicon esculentum). The deduced protein precursor with a ca lculated molecular weight of 23.8 kDa was predicted to target mitochondria and was classified as a plant MT-sHSP. A single copy of LeHSP23.8 was found in tomato genomic DNA by southern-blot analysis. Northern-blot analysis re vealed the heat inducible character of LeHSP23.8 mRNA. The LeHSP23.8 mRNA w as hardly detectable at about 36 degrees C but accumulated markedly at 40 d egrees C. The molecular chaperone function of LeHSP23.8 was confirmed in vi tro. The recombinant LeHSP23.8 was able to enhance the renaturation of chem ically denatured citrate synthase (CS). Moreover, the recombinant LeHSP23.8 protected CS from thermal inactivation and also promoted the renaturation of thermally inactivated citrate synthase.