Structure of native lens connexin 46/50 intercellular channels by cryo-EM

Gap junctions establish direct pathways for cell-to-cell communication through the assembly of twelve connexin subunits that form intercellular channels connecting neighbouring cells. Co-assembly of different connexin isoforms produces channels with unique properties and enables communication across cell types. Here we used single-particle cryo-electron microscopy to investigate the structural basis of connexin co-assembly in native lens gap junction channels composed of connexin 46 and connexin 50 (Cx46/50). We provide the first comparative analysis to connexin 26 (Cx26), which--together with computational studies--elucidates key energetic features governing gap junction permselectivity. Cx46/50 adopts an open-state conformation that is distinct from the Cx26 crystal structure, yet it appears to be stabilized by a conserved set of hydrophobic anchoring residues. 'Hot spots' of genetic mutations linked to hereditary cataract formation map to the core structural-functional elements identified in Cx46/50, suggesting explanations for many of the disease-causing effects.Cryo-electron microscopy structures of connexin channels composed of connexin 46 and connexin 50 in an open-state reveal features that govern permselectivity and the location of mutated residues linked to herediatry cataracts.
Author(s): Janette B. Myers [sup.1] , Bassam G. Haddad [sup.1] , Susan E. O'Neill [sup.1] , Dror S. Chorev [sup.2] , Craig C. Yoshioka [sup.3] , Carol V. Robinson [sup.2] [...]