TY - JOUR
T1 - Backbone amides are determinants of Cl− selectivity in CLC ion channels
AU - Leisle, Lilia
AU - Lam, Kin
AU - Dehghani-Ghahnaviyeh, Sepehr
AU - Fortea, Eva
AU - Galpin, Jason D.
AU - Ahern, Christopher A.
AU - Tajkhorshid, Emad
AU - Accardi, Alessio
N1 - Funding Information:
The authors thank members of the Accardi lab for helpful discussions. The work was supported by National Institutes of Health (NIH) grants R01-GM128420 (to A.A.), R01-GM106569 and NINDS R24 NS104617 (to C.A.A.), R01-GM123455 and P41-GM104601 (to E.T.). Simulations in this study have been performed using allocations at National Science Foundation Supercomputing Centers (XSEDE grant number MCA06N060), and the Blue Waters Petascale Computing Facility of National Center for Supercomputing Applications (NCSA) at University of Illinois at Urbana-Champaign, which is supported by the National Science Foundation (awards OCI-0725070 and ACI-1238993) and the State of Illinois.
Publisher Copyright:
© 2022, The Author(s).
PY - 2022/12
Y1 - 2022/12
N2 - Chloride homeostasis is regulated in all cellular compartments. CLC-type channels selectively transport Cl− across biological membranes. It is proposed that side-chains of pore-lining residues determine Cl− selectivity in CLC-type channels, but their spatial orientation and contributions to selectivity are not conserved. This suggests a possible role for mainchain amides in selectivity. We use nonsense suppression to insert α-hydroxy acids at pore-lining positions in two CLC-type channels, CLC-0 and bCLC-k, thus exchanging peptide-bond amides with ester-bond oxygens which are incapable of hydrogen-bonding. Backbone substitutions functionally degrade inter-anion discrimination in a site-specific manner. The presence of a pore-occupying glutamate side chain modulates these effects. Molecular dynamics simulations show backbone amides determine ion energetics within the bCLC-k pore and how insertion of an α-hydroxy acid alters selectivity. We propose that backbone-ion interactions are determinants of Cl− specificity in CLC channels in a mechanism reminiscent of that described for K+ channels.
AB - Chloride homeostasis is regulated in all cellular compartments. CLC-type channels selectively transport Cl− across biological membranes. It is proposed that side-chains of pore-lining residues determine Cl− selectivity in CLC-type channels, but their spatial orientation and contributions to selectivity are not conserved. This suggests a possible role for mainchain amides in selectivity. We use nonsense suppression to insert α-hydroxy acids at pore-lining positions in two CLC-type channels, CLC-0 and bCLC-k, thus exchanging peptide-bond amides with ester-bond oxygens which are incapable of hydrogen-bonding. Backbone substitutions functionally degrade inter-anion discrimination in a site-specific manner. The presence of a pore-occupying glutamate side chain modulates these effects. Molecular dynamics simulations show backbone amides determine ion energetics within the bCLC-k pore and how insertion of an α-hydroxy acid alters selectivity. We propose that backbone-ion interactions are determinants of Cl− specificity in CLC channels in a mechanism reminiscent of that described for K+ channels.
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U2 - 10.1038/s41467-022-35279-1
DO - 10.1038/s41467-022-35279-1
M3 - Article
C2 - 36473856
AN - SCOPUS:85143424783
SN - 2041-1723
VL - 13
JO - Nature Communications
JF - Nature Communications
IS - 1
M1 - 7508
ER -