THE ISOLATION AND CHARACTERIZATION OF A GENE ENCODING SUPEROXIDE-DISMUTASE FROM BRADYRHIZOBIUM SP (PARASPONIA) STRAIN ANU289

Bradyrhizobium sp. (Parasponia) strain ANU289 expresses a single Mn-SO D in both the vegetative and symbiotic states. A 500 bp sod-homologous sequence was amplified from genomic DNA of strain ANU289 using PCR. A 1.3 kb SalI fragment was subsequently cloned which contained an ORF, sodA, encoding a 23 Kd protein. This putative SOD shares considerable homology with other Mn-SODs and analysis of the sodA sequence predicts that it is expressed. A lacZ-sodA fusion complemented the SOD-deficie ncy of E. coli QC779 and resulted in the expression of SOD activity in both mutant and wild type E. coli. We conclude that sodA encodes the Mn-SOD of strain ANU289.