Folding correctors can restore CFTR posttranslational folding landscape by allosteric domain-domain coupling

The folding/misfolding and pharmacological rescue of multidomain ATP-binding cassette (ABC) C-subfamily transporters, essential for organismal health, remain incompletely understood. The ABCC transporters core consists of two nucleotide binding domains (NBD1,2) and transmembrane domains (TMD1,2). Using molecular dynamic simulations, biochemical and hydrogen deuterium exchange approaches, we show that the mutational uncoupling or stabilization of NBD1-TMD1/2 interfaces can compromise or facilitate the CFTR(ABCC7)-, MRP1(ABCC1)-, and ABCC6-transporters posttranslational coupled domain-folding in the endoplasmic reticulum. Allosteric or orthosteric binding of VX-809 and/or VX-445 folding correctors to TMD1/2 can rescue kinetically trapped CFTR posttranslational folding intermediates of cystic fibrosis (CF) mutants of NBD1 or TMD1 by global rewiring inter-domain allosteric-networks. We propose that dynamic allosteric domain-domain communications not only regulate ABCC-transporters function but are indispensable to tune the folding landscape of their posttranslational intermediates. These allosteric networks can be compromised by CF-mutations, and reinstated by correctors, offering a framework for mechanistic understanding of ABCC-transporters (mis)folding. The conformational biogenesis of multi-domain ABC-transporters is poorly understood. Here the authors show the critical role of dynamic allosteric coupling networks, its perturbation and restoration in CFTR folding, misfolding, and pharmacological rescue, respectively.

Automated summary

The folding and rescuing of multidomain ABC transporters have significant implications for organismal health. In this study, the authors employed molecular dynamic simulations, biochemical and hydrogen deuterium exchange approaches to investigate the mechanisms underlying the folding and rescue of ABCC transporters. It was found that modulating the interfaces between the nucleotide binding domains and transmembrane domains could affect the posttranslational coupled domain-folding in the endoplasmic reticulum. Furthermore, the use of folding correctors could rescue the folding intermediates of CFTR mutants by rewiring inter-domain allosteric networks.