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Elife 2023 Oct 02;12. doi: 10.7554/eLife.90736.
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Estimating the true stability of the prehydrolytic outward-facing state in an ABC protein.

Simon MA , Iordanov I , Szollosi A , Csanády L .

CFTR, the anion channel mutated in cystic fibrosis patients, is a model ABC protein whose ATP-driven conformational cycle is observable at single-molecule level in patch-clamp recordings. Bursts of CFTR pore openings are coupled to tight dimerization of its two nucleotide-binding domains (NBDs) and in wild-type (WT) channels are mostly terminated by ATP hydrolysis. The slow rate of non-hydrolytic closure - which determines how tightly bursts and ATP hydrolysis are coupled - is unknown, as burst durations of catalytic site mutants span a range of ~200-fold. Here, we show that Walker A mutation K1250A, Walker B mutation D1370N, and catalytic glutamate mutations E1371S and E1371Q all completely disrupt ATP hydrolysis. True non-hydrolytic closing rate of WT CFTR approximates that of K1250A and E1371S. That rate is slowed ~15-fold in E1371Q by a non-native inter-NBD H-bond, and accelerated ~15-fold in D1370N. These findings uncover unique features of the NBD interface in human CFTR.

PubMed ID: 37782012
PMC ID: PMC10569789
Article link: Elife
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: aopep cftr emd frzb2
GO keywords: anion channel activity [+]

Disease Ontology terms: cystic fibrosis

Article Images: [+] show captions
References [+] :
Aleksandrov, The First Nucleotide Binding Domain of Cystic Fibrosis Transmembrane Conductance Regulator Is a Site of Stable Nucleotide Interaction, whereas the Second Is a Site of Rapid Turnover. 2002, Pubmed