Molecular Cloning, Expression and Characterization of Matrix Metalloproteinase-2 from Pacific White Shrimp (Litopenaeus vannamei) and Its Involvement in Protein Degradation

Matrix metalloproteinases (MMPs) play essential roles in the metabolism of collagens; however, information regarding MMPs in aquatic animals is limited. To elucidate the specific role of MMPs in shrimp muscle degradation, proteinases with gelatinolytic activity were identified in the hepatopancreas of Litopenaeus vannamei (Lv). The gelatinolytic activity was suppressed by metalloproteinase inhibitors EDTA and EGTA to some degree, suggesting the existence of metalloproteinases. Then the catalytic domain of LvMMP-2 (LvMMP-2c) was cloned and expressed heterologously in the Pichia pastoris expression system. rLvMMP-2c (recombinant LvMMP-2c) demonstrated optimal gelatinolytic activity at pH 8.0 and 50 °C, and its activity could be enhanced by Ca²⁺ and Ba²⁺. Type I collagen and myofibrillar proteins from shrimp were effectively hydrolyzed by rLvMMP-2c not only at 37 °C, but also at 4 °C, indicating its involvement in the postmortem tenderization of shrimp muscle. Our present study provided new information to elucidate the role of metalloproteinase underlying shrimp meat softening during cold storage, and suggested new strategies to prevent shrimp quality decrement during cold storage.