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A defective flexible loop contributes to the processing and gating defects of the predominant cystic fibrosis‐causing mutation
Author(s) -
Chen Xinying,
Zhu Siyu,
Zhenin Michael,
Xu Weiyi,
Bose Samuel J.,
Wong Molly PikFan,
Leung George P. H.,
Senderowitz Hanoch,
Chen JengHaur
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.201801218rr
Subject(s) - cystic fibrosis transmembrane conductance regulator , δf508 , cystic fibrosis , mutation , gating , mutant , biology , chemistry , microbiology and biotechnology , genetics , gene , biophysics
People with the genetic disease cystic fibrosis (CF) often carry a deletion mutation ∆F508 on the gene encoding the CF transmembrane conductance regulator (CFTR) Cl − 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 ∆F508‐CFTR. Most deletion mutations, but not alanine substitutions, of individual residues from positions 503 to 513 impaired CFTR maturation. Interestingly, only protein processing of ∆Y512‐CFTR, like that of ∆F508‐CFTR, was greatly improved by low‐temperature culture at 27°C or small‐molecule corrector C18. The 2 mutant Cl − 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 G5091 position backward in the loop, markedly enhanced ∆F508‐CFTR maturation and opening rate while promoting protein stability and persistence of the H3 helix in ∆F508 nucleotide‐binding domain 1. Moreover, V510A/S511A mutations noticeably increased ∆Y512‐CFTR maturation at 27°C and its opening rate. Thus, loop abnormalities may contribute to ∆F508‐ and ∆Y512‐CFTR defects. Importantly, correcting defects from G509 displacement in ∆F508‐CFTR may offer a new avenue for drug discovery and CF treatments.—Chen, X., Zhu, S., Zhenin, M., Xu, W., Bose, S. J., Wong, M. P.‐F., Leung, G. P. H., Senderowitz, H., Chen, J.‐H. A defective flexible loop contributes to the processing and gating defects of the predominant cystic fibrosis‐causing mutation. FASEB J. 33, 5126–5142 (2019). www.fasebj.org