Atomic model of human cystic fibrosis transmembrane conductance regulator: Membrane-spanning domains and coupling interfaces

Abstract

We describe herein an atomic model of the outward-facing three-dimensional structure of the membrane-spanning domains (MSDs) and nucleotide-binding domains (NBDs) of human cystic fibrosis transmembrane conductance regulator (CFTR), based on the experimental structure of the bacterial transporter Sav1866. This model, which is in agreement with previous experimental data, highlights the role of some residues located in the transmembrane passages and directly involved in substrate translocation and of some residues within the intracellular loops (ICL1-ICL4) making MSD/NBD contacts. In particular, our model reveals that D173 ICL1 and N965 ICL3 likely interact with the bound nucleotide and that an intricate H-bond network (involving especially the ICL4 R1070 and the main chain of NBD1 F508) may stabilize the interface between MSD2 and the NBD1F508 region. These observations allow new insights into the ATP-binding sites asymmetry and into the molecular consequences of the F508 deletion, which is the most common cystic fibrosis mutation.

Pharmacological Rescue of the Mutant Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Detected by Use of a Novel Fluorescence Platform

“…One possibility is that each corrector interacts with a different structural feature of F508del-CFTR to stabilize their folding or reduce nonproductive folding intermediates. Because the folding defect of F508del involves multiple domain and interdomain interactions, multiple interaction sites may be necessary for optimal correction of the misfolded protein (33)(34)(35)(36)(37). Alternatively, rescue might be achieved indirectly through the modulation of folding chaperones or by suppressing ER-associated degradation (ERAD) quality control pathways that promote F508del-CFTR ubiquitylation and degradation.…”

Molecular Dynamics Flexible Fitting Simulations Identify New Models of the Closed State of the Cystic Fibrosis Transmembrane Conductance Regulator Protein

“…The outward facing models 14,[17][18][19][20][21][22][23] were based primarily on the Sav1866 structure as a template, 24 although recently the newly solved ABC transporter structure McjD 25 has been used to model this state. 26 Inward facing models were based either on the bacterial MsbA 27 or on the P-gp 28 structures.…”

Two Salt Bridges Differentially Contribute to the Maintenance of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Channel Function

“…Dysfunction of CFTR is directly associated with three devastating diseases: cystic fibrosis, polycystic kidney disease, and secretory diarrhea. Based on functional data and homology models, CFTR has been predicted to contain five functional domains: two membranespanning domains (MSDs), each including six transmembrane (TM) helices; two nucleotide binding domains (NBD1 and NBD2); and a unique regulatory (R) domain, which carries multiple protein kinase A (PKA) consensus phosphorylation sites and is unique to CFTR in the ABC superfamily (1)(2)(3)(4)(5)(6). Functional studies from multiple groups have suggested that TM6 plays an essential role and TM12 contributes less to anion conduction and permeation properties in the CFTR channel pore (7)(8)(9)(10)(11).…”