Molecular dynamics and functional characterization of I37R-CFTR lasso mutation provide insights into channel gating activity

Sharon L Wong; Nikhil T Awatade; Miro A Astore; Katelin M Allan; Michael J Carnell; Iveta Slapetova; Po-Chia Chen; Alexander Capraro; Laura K Fawcett; Renee M Whan; Renate Griffith; Chee Y Ooi; Serdar Kuyucak; Adam Jaffe; Shafagh A Waters

doi:10.1016/j.isci.2021.103710

Molecular dynamics and functional characterization of I37R-CFTR lasso mutation provide insights into channel gating activity

iScience. 2021 Dec 31;25(1):103710. doi: 10.1016/j.isci.2021.103710. eCollection 2022 Jan 21.

Authors

Sharon L Wong^{1

2}, Nikhil T Awatade^{1

2}, Miro A Astore³, Katelin M Allan^{1

2}, Michael J Carnell⁴, Iveta Slapetova⁴, Po-Chia Chen³, Alexander Capraro^{1

2}, Laura K Fawcett^{1

2

5}, Renee M Whan⁴, Renate Griffith⁶, Chee Y Ooi^{1

2

7}, Serdar Kuyucak³, Adam Jaffe^{1

2

5}, Shafagh A Waters^{1

2

5}

Affiliations

¹ School of Women's and Children's Health, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia.
² Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), UNSW Sydney, Sydney, Australia.
³ School of Physics, University of Sydney, Sydney, Australia.
⁴ Katharina Gaus Light Microscopy Facility, Mark Wainwright Analytical Centre, UNSW Sydney, Sydney, Australia.
⁵ Department of Respiratory Medicine, Sydney Children's Hospital, Randwick, Australia.
⁶ School of Chemistry, UNSW Sydney, Sydney, Australia.
⁷ Department of Gastroenterology, Sydney Children's Hospital, Randwick, Australia.

Abstract

Characterization of I37R, a mutation located in the lasso motif of the CFTR chloride channel, was conducted by theratyping several CFTR modulators from both potentiator and corrector classes. Intestinal current measurements in rectal biopsies, forskolin-induced swelling (FIS) in intestinal organoids, and short circuit current measurements in organoid-derived monolayers from an individual with I37R/F508del CFTR genotype demonstrated that the I37R-CFTR results in a residual function defect amenable to treatment with potentiators and type III, but not type I, correctors. Molecular dynamics of I37R using an extended model of the phosphorylated, ATP-bound human CFTR identified an altered lasso motif conformation which results in an unfavorable strengthening of the interactions between the lasso motif, the regulatory (R) domain, and the transmembrane domain 2 (TMD2). Structural and functional characterization of the I37R-CFTR mutation increases understanding of CFTR channel regulation and provides a potential pathway to expand drug access to CF patients with ultra-rare genotypes.

Keywords: Biochemistry; Pharmacology; Structural biology.