Abstract
Cone snail venoms contain a wide variety of bioactive peptides, including insulin-like molecules with distinct structural features, binding modes, and biochemical properties. Here, we report a fully active humanized cone snail venom insulin with an elongated A chain and a truncated B chain, and use cryo-electron microscopy and protein engineering to elucidate its interactions with the human insulin receptor ectodomain. We reveal how an extended A chain can compensate for deletion of B-chain residues, which are essential for activity of native insulin but also compromise therapeutic utility by delaying the onset action, suggesting approaches to develop improved therapeutic insulins. Curiously, a receptor conformation present in low abundance adopts a highly asymmetric structure that displays novel coordination of a single humanized venom insulin using elements from both of the previously characterized site 1 and site 2 interactions.
Decision letter: Fish-hunting cone snail venoms are a rich source of minimized ligands of the vertebrate insulin receptor
