Ligand- and Subunit-specific Conformational Changes in the Ligand-binding Domain and the TM2-TM3 Linker of α1 β2 γ2 GABAA Receptors

被引:17
|
作者
Wang, Qian
Pless, Stephan A.
Lynch, Joseph W. [1 ]
机构
[1] Univ Queensland, Queensland Brain Inst, Brisbane, Qld 4072, Australia
基金
英国医学研究理事会; 澳大利亚研究理事会;
关键词
NICOTINIC ACETYLCHOLINE-RECEPTOR; DISTINCT STRUCTURAL-CHANGES; GATED ION-CHANNEL; CRYSTAL-STRUCTURE; LOOP F; BENZODIAZEPINE MODULATION; SIGNAL-TRANSDUCTION; GATING MECHANISM; PROTEIN MOBILITY; GLYCINE;
D O I
10.1074/jbc.M110.161513
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Cys-loop receptor ligand binding sites are located at subunit interfaces where they are lined by loops A-C from one subunit and loops D-F from the adjacent subunit. Agonist binding induces large conformational changes in loops C and F. However, it is controversial as to whether these conformational changes are essential for gating. Here we used voltage clamp fluorometry to investigate the roles of loops C and F in gating the alpha 1 beta 2 gamma 2 GABA(A) receptor. Voltage clamp fluorometry involves labeling introduced cysteines with environmentally sensitive fluorophores and inferring structural rearrangements from ligand-induced fluorescence changes. Previous attempts to define the roles of loops C and F using this technique have focused on homomeric Cys-loop receptors. However, the problem with studying homomeric receptors is that it is difficult to eliminate the possibility of bound ligands interacting directly with attached fluorophores at the same site. Here we show that ligands binding to the beta 2-alpha 1 interface GABA binding site produce conformational changes at the adjacent subunit interface. This is most likely due to agonist-induced loop C closure directly altering loop F conformation at the adjacent alpha 1-beta 2 subunit interface. However, as antagonists and agonists produce identical alpha 1 subunit loop F conformational changes, these conformational changes appear unimportant for gating. Finally, we demonstrate that TM2-TM3 loops from adjacent beta 2 subunits in alpha 1 beta 2 receptors can dimerize via K24'C disulfides in the closed state. This result implies unexpected conformational mobility in this crucial part of the gating machinery. Together, this information provides new insights into the activation mechanisms of Cys-loop receptors.
引用
收藏
页码:40373 / 40386
页数:14
相关论文
共 50 条
  • [31] Ligand binding domain interface: A tipping point for pharmacological agents binding with GluN1/2A subunit containing NMDA receptors
    Bledsoe, Douglas
    Vacca, Bryanna
    Laube, Bodo
    Klein, Bradley G.
    Costa, Blaise
    EUROPEAN JOURNAL OF PHARMACOLOGY, 2019, 844 : 216 - 224
  • [32] PH-DEPENDENCE OF LIGAND-BINDING TO D-2 DOPAMINE-RECEPTORS
    DSOUZA, UM
    STRANGE, PG
    BIOCHEMISTRY, 1995, 34 (41) : 13635 - 13641
  • [33] Structural insights into conformational changes of Arp2/3 complex, induced by ligand binding
    Chemeris, A.
    Guo, S.
    Gautreau, A.
    Goode, B.
    Sokolova, O.
    FEBS JOURNAL, 2015, 282 : 220 - 221
  • [34] CONFORMATIONAL-CHANGES IN THE CHICKEN RECEPTOR FOR ENDOCYTOSIS OF GLYCOPROTEINS - MODULATION OF LIGAND-BINDING ACTIVITY BY CA-2+ AND PH
    LOEB, JA
    DRICKAMER, K
    JOURNAL OF BIOLOGICAL CHEMISTRY, 1988, 263 (20) : 9752 - 9760
  • [35] HIGH-AFFINITY LIGAND-BINDING TO SUBUNIT H1 OF THE ASIALOGLYCOPROTEIN RECEPTOR IN THE ABSENCE OF SUBUNIT H2
    BIDER, MD
    CESCATO, R
    JENO, P
    SPIESS, M
    EUROPEAN JOURNAL OF BIOCHEMISTRY, 1995, 230 (01): : 207 - 212
  • [36] Crystal structure of the ligand-binding domain of the receptor tyrosine kinase EphB2
    Juha-Pekka Himanen
    Mark Henkemeyer
    Dimitar B. Nikolov
    Nature, 1998, 396 : 486 - 491
  • [37] Crystal structure of the ligand-binding domain of the receptor tyrosine kinase EphB2
    Himanen, JP
    Henkemeyer, M
    Nikolov, DB
    NATURE, 1998, 396 (6710) : 486 - 491
  • [38] Structural insights into the ligand binding domain of GluD1 and GluD2 receptors
    Tricoire, Ludovic
    Hepp, Regine
    FEBS JOURNAL, 2023, 290 (15) : 3745 - 3747
  • [39] A mutation in the ligand-binding domain can restore normal gating in an alcohol-insensitive GLUN2A NMDAR subunit
    Fellbaum, C. M.
    McKee, J. L.
    Peoples, R. W.
    ALCOHOL-CLINICAL AND EXPERIMENTAL RESEARCH, 2023, 47 : 476 - 476
  • [40] The actions of ether, alcohol and alkane general anaesthetics on GABAA and glycine receptors and the effects of TM2 and TM3 mutations
    Krasowski, MD
    Harrison, NL
    BRITISH JOURNAL OF PHARMACOLOGY, 2000, 129 (04) : 731 - 743