Coiled-Coil Domain Kinking Controls Laminin-332 Cleavage by Elastase.

Laminins are integral components of basement membranes, where they provide structural support and mediate integrin-dependent cell adhesion. A flexible coiled-coil domain forms the laminin long arm, but ultrastructural insight into this domain is limited, and the function of coiled-coil flexibility remains unclear. Here, we use high-speed atomic force microscopy (HS-AFM) to visualize, in real-time, the digestion of individual laminin-332 molecules by pancreatic elastase and show that coiled-coil kinking directs elastase cleavage to the hinge site, thereby generating the elastase 8 (E8) fragment containing the C-terminal integrin-binding site. In contrast, coiled-coil domains in extended conformations are cleaved at arbitrary sites, resulting in complete coiled-coil degradation. By integrating HS-AFM with AlphaFold structure prediction and normal-mode flexible fitting (NMFF), we furthermore generate dynamic models of the laminin-332 hinge during coiled-coil kinking, providing atomic-scale insight into the underlying flexing mechanism. Our results thus identify a novel conformational control mechanism directing proteolytic processing of laminin-332 through defined coiled-coil kinking.