Conformational changes relevant to channel activity and folding within the first nucleotide binding domain of the cystic fibrosis transmembrane conductance regulator.
Deletion of Phe-508 (F508del) in the first nucleotide binding domain (NBD1) of the cystic fibrosis transmembrane conductance regulator (CFTR) leads to defects in folding and channel gating. NMR data on human F508del NBD1 indicate that an H620Q mutant, shown to increase channel open probability, and the dual corrector/potentiator CFFT-001 similarly disrupt interactions between β-strands S3, S9, and S10 and the C-terminal helices H8 and H9, shifting a preexisting conformational equilibrium from helix to coil. CFFT-001 appears to interact with β-strands S3/S9/S10, consistent with docking simulations. Decreases in T(m) from differential scanning calorimetry with H620Q or CFFT-001 suggest direct compound binding to a less thermostable state of NBD1. We hypothesize that, in full-length CFTR, shifting the conformational equilibrium to reduce H8/H9 interactions with the uniquely conserved strands S9/S10 facilitates release of the regulatory region from the NBD dimerization interface to promote dimerization and thereby increase channel open probability. These studies enabled by our NMR assignments for F508del NBD1 provide a window into the conformational fluctuations within CFTR that may regulate function and contribute to folding energetics.
Molecular Structure and Function Program, Hospital for Sick Children and Department of Biochemistry, University of Toronto, Toronto, Ontario M5S1A8, Canada.
Rhea P
RP
Hudson
P Andrew
PA
Chong
Irina I
II
Protasevich
Robert
R
Vernon
Efrat
E
Noy
Hermann
H
Bihler
Jian Li
JL
An
Ori
O
Kalid
Inbal
I
Sela-Culang
Martin
M
Mense
Hanoch
H
Senderowitz
Christie G
CG
Brouillette
Julie D
JD
Forman-Kay
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020125:Mutation, Missense; D017510:Protein Folding; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator