Tissue-specific expression and molecular modeling of cytosolic manganese superoxide dismutases from the white shrimp Litopenaeus vannamei

Manganese superoxide dismutases (MnSODs) are usually mitochondrial enzymes, although there are few examples of cytosolic MnSODs (cMnSOD). We have previously characterized a cMnSOD cDNA from Litopenaeus vannamei hemocytes, and to obtain new insights into the tissue specific expression and the protein structure, we characterized three more different cMnSOD transcripts (cMnsod1, cMnsod2 and cMnsod3) and modeled the three-dimensional protein structure using human MnSOD as a template. The nucleotide sequences differ in seven positions. Four differences are silent; while three produce changes in amino acid sequence. cMnsod1, cMnsod2 and cMnsod3 are differentially expressed in nervous system, hepatopancreas and hemocytes. The structural protein model predicts bona fide MnSODs with proper coordination for the enzymatic activity.