A thermostable manganese-containing superoxide dismutase from pathogen Chlamydia pneumoniae.

The gene CP0718 encoding a putative manganese-containing superoxide dismutase of Chlamydia pneumoniae AR39 was cloned and expressed in Escherichia coli. Characterization showed that the expressed protein with a monomeric molecular mass of 23.1 kDa had superoxide dismutase (SOD) activity and the cofactor of CpSOD was a bivalent manganese cation. It is unexpected that this enzyme was hyperthermostable, and maintained about 90% activity after incubation at 70 degrees C for 60 min. Manganese binding residues found in the SOD sequences from different species are conserved in CpSOD. Bioinformatics analysis compared with Propionibacterium shermanii MnSOD was performed to elucidate the CpSOD hyperthermostability based on amino acid sequences.