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

Gap junctions establish direct pathways for cell-to-cell communication, through the assembly of twelve subunits (connexins) that form intercellular channels connecting neighboring cells. Co-assembly of different connexin isoforms produces channels with unique properties, and enables communication across cell-types. To gain access into the structural underpinnings of connexin co-assembly, we used single particle CryoEM to determine the structure of 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 perm-selectivity. Cx46/50 adopts an open-state conformation that is unique from the Cx26 crystal structure, yet 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, rationalizing many of the disease-causing effects.

Citation

Janette B. Myers, Bassam G. Haddad, Susan E. O’Neill, Dror S. Chorev, Craig C. Yoshioka, Carol V. Robinson, Daniel M. Zuckerman, Steve L. Reichow. Structure of native lens connexin-46/50 intercellular channels by CryoEM Nature. 2018 Dec 12;564(7736):372-377

PMID: 30542154

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