title: Conformational changes during human P2X7 receptor activation examined by structural modelling and cysteine-based cross-linking studies.
abstract: The P2X7 receptor (P2X7R) is important in mediating a range of physiological functions and pathologies associated with tissue damage and inflammation and represents an attractive therapeutic target. However, in terms of their structure-function relationships, the mammalian P2X7Rs remain poorly characterised compared to some of their other P2XR counterparts. In this study, combining cysteine-based cross-linking and whole-cell patch-clamp recording, we examined six pairs of residues (A44/I331, D48/I331, I58/F311, S60/L320, I75/P177 and K81/V304) located in different parts of the extracellular and transmembrane domains of the human P2X7R. These residues are predicted to undergo substantial movement during the transition of the receptor ion channel from the closed to the open state, predictions which are made based on structural homology models generated from the crystal structures of the zebrafish P2X4R. Our results provide evidence that among the six pairs of cysteine mutants, D48C/I133C and K81C/V304C formed disulphide bonds that impaired the channel gating to support the notion that such conformational changes, particularly those in the outer ends of the transmembrane domains, are critical for human P2X7R activation.
authors.affiliation: School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Caseley
authors.affiliation: School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Muench
authors.affiliation: School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK. l.h.jiang@leeds.ac.uk.
authors.forename: Lin-Hua
authors.identifier: 0000-0001-6398-0411
authors.initials: LH
authors.lastname: Jiang
mesh_terms: D003545:Cysteine; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D008958:Models, Molecular; D011487:Protein Conformation; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism*
chemical_list: D058486:Receptors, Purinergic P2X7; D003545:Cysteine
keywords: Cross linking; Cysteine substitution; Disulphide bond; Ion channel gating; P2X7 receptor