Trikafta rescues F508del-CFTR by tightening specific phosphorylation-dependent interdomain interactions

Abstract

Trikafta is well-known for correcting the thermal and gating defects caused by the most common cystic fibrosis mutation F508del in the human cystic fibrosis transmembrane conductance regulator even at physiological temperature. However, the exact pathway is still unclear. Here, the noncovalent interactions among two transmembrane domains (TMD 1 and TMD2), the regulatory (R) domain and two nucleotide binding domains (NBD1 and NBD2), along with the thermoring structures of NBD1, were analyzed around the active gating center. The results demonstrated that Trikafta binding to TMD1 and TMD2 rearranged their interactions with the R domain, releasing the C-terminal region from NBD1 for its tight ATP-dependent dimerization with NBD2, stabilizing NBD1. Taken together, although the deletion of F508 induces the primary thermal defect of NBD1 and then the gating defect at the TMD1-TMD2 interface, Trikafta rescued them in a reverse manner allosterically. Thus, the thermoring structure can be used to uncover the pathway of a drug to correct the thermal defect of health-related protein.