MOLECULAR-CLONING AND CHARACTERIZATION OF 2 IRON SUPEROXIDE-DISMUTASECDNAS FROM TRYPANOSOMA-CRUZI

Two cDNAs (FeSODA and FeSODB cDNAs) corresponding to superoxide dismut ase (1.15.1.1., SOD) were isolated from a Trypanosoma cruzi cDNA libra ry. Comparison of the deduced amino acid sequences with previously rep orted SOD protein sequences revealed that the T. cruzi open reading fr ames had considerable homology with FeSODs. The coding region of the T . cruzi FeSODB cDNA has been expressed in fusion with glutathione-S-tr ansferase using an Escherichia coli mutant QC779, lacking both MnSOD a nd FeSOD genes (sodA sodB). Staining of native polyacrylamide gels for SOD activity of T cruzi crude lysate and the recombinant SOD suggests that this protein is an FeSOD. The recombinant enzyme also protected the E. coli mutant QC779 from paraquat toxicity. Northern blot analysi s showed that FeSODB is differentially expressed, showing a higher lev el at the epimastigote stage of T. cruzi development; whereas, FeSODA is constitutively expressed al a lower level in all developmental stag es, Furthermore, Southern hybridization shows that both FeSODA and FeS ODB genes appear to be present in the T. cruzi genome as multiple repe ating units (multi-copy gene family). (C) 1997 Elsevier Science B.V.