| Abstract |
In this study, we describe the identification and characterization of manganese superoxide dismutase, an important antioxidant enzyme acting as the chief reactive oxygen species (ROS) scavenger, from rock bream Oplegnathus fasciatus (Of-mMnSOD) at genomic- and transcriptional-levels as well as the biological activity of translated protein. In silico analysis revealed that deduced Of-mMnSOD protein portrayed distinct MnSOD family features including signature motifs, metal association sites and the typical active site topology. It was also predicted to be localized in mitochondrial matrix. Furthermore, sequence homology data and quinquepartite genome organization encompassing five exons interrupted by four introns reinforced a strong conservation of MnSOD among different vertebrate lineages. Basal- and temporal-expressional analysis performed by quantitative real time PCR demonstrated that Of-mMnSOD was ubiquitously transcribed in different rock bream tissues with higher levels in blood cells and metabolically active tissues, and Of-mMnSOD expression was significantly modulated in response to investigational challenges using mitogens (lipopolysaccharide and poly I:C) and live-pathogens (Edwardsiella tarda and rock bream iridovirus) in blood cells and liver tissue. While Of-mMnSOD promoter region lacked a TATA box or CAAT box, analysis of putative cis regulatory elements in promoter proximal region supported the inducible responsiveness of Of-mMnSOD to different challenges. Besides, in vitro antioxidant assay using purified recombinant Of-mMnSOD (rOf-mMnSOD) protein in a xanthine/xanthine oxidase system showed that rOf-mMnSOD possessed potential antioxidant capacity and actively survived over a range of pH (7.5-11) and temperature (15-40ºC) conditions. Collectively, findings of this study suggest that Of-mMnSOD combats against oxidative stress and cellular damages induced by mitogen/pathogen-mediated inflammation, by detoxifying harmful ROS (O2●-) in rock bream. |
