The P2/P2' sites affect the substrate cleavage of TNF-α converting enzyme (TACE)

Tumor necrosis factor-alpha converting enzyme (TACE) is a proteinase that releases over eighty soluble proteins from their membrane-bound forms, and it has long been an intriguing therapeutic target in auto-immune diseases, and recently, in cancers. However, a haunting question is how TACE recognizes its substrates. In this work, we applied computational and experimental methods to study the role of the P2 site and the P2' site of the substrate peptide in the substrate cleavage of TACE. In the computational complex model, the sidechains of these residues do not form key interactions with TACE, but experimentally, the mutations at these two positions largely affect the peptide cleavage efficiency in the enzymatic assay. We then showed that the P2/P2' sites could affect the efficiency of the conformation search for the correct peptide orientation, which in turn affects the substrate cleavage efficiency. Our result provides new information to the better understanding of the enzymatic mechanism of TACE, and could be useful in the design of novel TACE inhibitors.