A defective flexible loop contributes to the processing and gating defects of the predominant cystic fibrosis-causing mutation

Xinying Chen, Siyu Zhu, Michael Zhenin, Weiyi Xu, Samuel J. Bose, Molly Pik Fan Wong, George P.H. Leung, Hanoch Senderowitz, Jeng Haur Chen

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


People with the genetic disease cystic fibrosis (CF) often carry a deletion mutation DF508 on the gene encoding the CF transmembrane conductance regulator (CFTR) Cl2 channel. This mutation greatly reduces the CFTR maturation process and slows the channel opening rate. Here, we investigate whether residues near F508 contribute to these defects in DF508-CFTR. Most deletion mutations, but not alanine substitutions, of individual residues from positions 503 to 513 impaired CFTR maturation. Interestingly, only protein processing of DY512-CFTR, like that of DF508-CFTR, was greatly improved by low-temperature culture at 27°C or small-molecule corrector C18. The 2 mutant Cl2 channels were equally slow to open, suggesting that they may share common structural flaws. Studies on the H3-H4 loop that links residues F508 and Y512 demonstrate that G509A/V510G mutations, moving G509 1 position backward in the loop, markedly enhanced DF508-CFTR maturation and opening rate while promoting protein stability and persistence of the H3 helix in DF508 nucleotide-binding domain 1. Moreover, V510A/S511A mutations noticeably increased DY512-CFTR maturation at 27°C and its opening rate. Thus, loop abnormalities may contribute to DF508- and DY512-CFTR defects. Importantly, correcting defects from G509 displacement in DF508-CFTR may offer a new avenue for drug discovery and CF treatments.

Original languageEnglish
Pages (from-to)5126-5142
Number of pages17
JournalFASEB Journal
Issue number4
StatePublished - Apr 2019

Bibliographical note

Funding Information:
The authors thank Prof. Michael J. Welsh (University of Iowa, Iowa City, IA, USA) for generous gifts of WT human CFTR plasmids, Prof. Robert J. Bridges (Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA) and Cystic Fibrosis Foundation Therapeutics for providing the CFTR correctors, and departmental colleagues for valuable discussions. The authors acknowledge S. M. Chan for great assistance with experiments. This work was supported by grants from the Hong Kong Research Grants Council (789713M and 17106315) and National Natural Science Foundation of China (31370765 and 81570001) to J.-H.C. This work was also supported by grants from the Cystic Fibrosis Foundation Therapeutics (SENDER13XX0) and Binational Science Foundation (2013391) to H.S. In addition, X.C., S.Z., and W.X. were recipients of postgraduate scholarships from the University of Hong Kong. W.X. was also a recipient of Lee Shau Kee Postgraduate Fellowship at the University of Hong Kong. S.J.B. was the recipient of a Collaborative Awards in Science and Engineering (CASE) studentship from the Medical Research Council (Grant MR/L015919/1). The authors declare no conflicts of interest.

Publisher Copyright:
© 2019 FASEB. All rights reserved.


  • CFTR
  • Chloride channel
  • Corrector C18
  • DF508 mutation
  • Low temperature


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