Structural Basis for Selective Proteolysis of ADAM10 Substrates at Membrane-Proximal Sites

The endopeptidase ADAM10 is a critical catalyst for regulated proteolysis of key drivers of mammalian development and physiology, and for non-amyloidogenic cleavage of the Alzheimers precursor protein as the primary -secretase. ADAM10 function in vivo requires formation of a complex with a C8-tetraspanin protein, with different ADAM10-C8-tetraspanin complexes having distinct substrate selectivity, yet the basis for such selectivity remains elusive. We present here a cryo-EM structure of a vFab-ADAM10-Tspan15 complex, which shows that Tspan15 binding relieves ADAM10 autoinhibition and positions the enzyme active site about 20 [A] from the plasma membrane for membrane-proximal substrate cleavage. Cell-based assays of N-cadherin shedding establish that the positioning of the active site by the interface between the ADAM10 catalytic domain and the bound tetraspanin influences selection of the preferred cleavage site. Together, these studies reveal the molecular mechanism underlying selective ADAM10 proteolysis at membrane-proximal sites and offer a roadmap for its modulation in disease.