Molecular Modeling and Phylogeny of the Manganese Superoxide Dismutase from the Camel, Camelus dromedarius

The manganese superoxide dismutase (MnSOD or SOD2) is an important antioxidant enzyme in mammals as it eliminates the reactive oxygen species (ROS) produced by the aerobic reactions. The one-humped camel (Camelus dromedarius) is adapted to live in the widely varying arid climate and in many intrinsic and extrinsic ROS producing agents. Studying the MnSOD in C. dromedarius could help understand the impact of exposure to such factors on the health status of camel. The coding sequence of MnSOD of C. dromedarius (cSOD2) was amplified by reverse transcription PCR from the liver. The cDNA sequencing revealed an open reading frame of 666 nucleotides encoding a protein of 222 amino acids which is comparable to the SOD2 genes from many eukaryotic organisms. The calculated molecular weight and isoelectric point of cSOD2 were 24.6 kDa and 8.15, respectively. The amino acid sequence analysis revealed the presence of the mitochondria targeting sequence at the N-terminus, the conservation of the characteristic MnSOD motif signature and the four manganese binding sites in cSOD2. The alignment and phylogenetic analysis of the cSOD2 with sequences from 18 organisms indicated that cSOD2 groups with mammals which took late evolutionary line different from SOD2 from birds, amphibians, fish and invertebrates.