cDNA cloning of oyster matrix metalloproteinase and its possible involvement in hypoxic adaptation

ABSTRACT:   We have cloned a cDNA encoding the matrix metalloproteinase (MMP) from oyster Crassostrea gigas . The clone contains a 1797 bp open reading frame encoding a protein of 599 amino acids. Oyster MMP (Cg-MMP) has a transmembrane domain at its C-terminal and a furin/prohormone convertase cleavage site at the end of a propeptide domain, which are commonly observed in membrane-type MMPs (MT-MMPs). This suggests that Cg-MMP is an MT-MMP. The deduced amino acid sequence of oyster MMP shares approximately 30% identity with human MT4-MMP and MMPs from fruit fly and hydra. Cg-MMP mRNA was detected in the gill, mantle and adductor muscle, and more intense signals in the northern blot analysis were recognized in the gill and adductor muscle. Similar tissue distribution was observed for tissue inhibitor of metalloproteinase (Cg-TIMP) in oyster. In response to hypoxic stress, the abundance of Cg-MMP mRNA was elevated in the gill, while that of Cg-TIMP mRNA remained almost constant. These findings suggest that promotion of collagen metabolism may be implicated in the hypoxic adaptation in oyster.