CFTR channel opening by ATP-driven tight dimerization of its nucleotide-binding domains.
ABC (ATP-binding cassette) proteins constitute a large family of membrane proteins that actively transport a broad range of substrates. Cystic fibrosis transmembrane conductance regulator (CFTR), the protein dysfunctional in cystic fibrosis, is unique among ABC proteins in that its transmembrane domains comprise an ion channel. Opening and closing of the pore have been linked to ATP binding and hydrolysis at CFTR's two nucleotide-binding domains, NBD1 and NBD2 (see, for example, refs 1, 2). Isolated NBDs of prokaryotic ABC proteins dimerize upon binding ATP, and hydrolysis of the ATP causes dimer dissociation. Here, using single-channel recording methods on intact CFTR molecules, we directly follow opening and closing of the channel gates, and relate these occurrences to ATP-mediated events in the NBDs. We find that energetic coupling between two CFTR residues, expected to lie on opposite sides of its predicted NBD1-NBD2 dimer interface, changes in concert with channel gating status. The two monitored side chains are independent of each other in closed channels but become coupled as the channels open. The results directly link ATP-driven tight dimerization of CFTR's cytoplasmic nucleotide-binding domains to opening of the ion channel in the transmembrane domains. This establishes a molecular mechanism, involving dynamic restructuring of the NBD dimer interface, that is probably common to all members of the ABC protein superfamily.
Vergani
Paola
P
Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, New York 10021, USA. paola.vergani@rockefeller.edu
Lockless
Steve W
SW
Nairn
Angus C
AC
Gadsby
David C
DC
D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology*; D020134:Catalytic Domain; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004594:Electrophysiology; D006801:Humans; D006868:Hydrolysis; D015640:Ion Channel Gating / Q000187:drug effects*; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D020836:Protein Structure, Quaternary / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D013816:Thermodynamics
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000255:Adenosine Triphosphate
Annu Rev Biochem. 2004;73:241-68
15189142
Science. 2002 May 10;296(5570):1091-8
12004122
J Biol Chem. 2004 Jul 23;279(30):31212-20
15159388
Nat Struct Mol Biol. 2004 Oct;11(10):918-26
15452563
Annu Rev Biochem. 1980;49:877-919
6250450
Biochemistry. 1990 Oct 9;29(40):9343-52
2248951
J Biol Chem. 1995 Jan 27;270(4):1711-7
7530246
Cell. 1995 Jul 28;82(2):231-9
7543023
Biochem J. 1997 May 1;323 ( Pt 3):777-83
9169612
Nature. 1998 Dec 17;396(6712):703-7
9872322
J Mol Biol. 2003 Nov 28;334(3):403-19
14623183
J Mol Biol. 2003 Nov 21;334(2):255-67
14607117
Mol Cell. 2003 Sep;12(3):651-61
14527411
J Gen Physiol. 2003 Sep;122(3):333-48
12939393
J Biol Chem. 2003 Jul 18;278(29):26862-9
12746444
J Mol Biol. 2003 Jul 4;330(2):343-58
12823973
Curr Opin Struct Biol. 2003 Apr;13(2):249-55
12727520
J Gen Physiol. 2003 Jan;121(1):17-36
12508051
Mol Cell. 2002 Jul;10(1):139-49
12150914
J Biol Chem. 2002 Jun 14;277(24):21111-4
11964392
Science. 1999 Oct 8;286(5438):295-9
10514373
J Biol Chem. 2002 May 3;277(18):15419-25
11861646
J Biol Chem. 2001 Oct 19;276(42):38636-44
11507101
Cell. 2000 Jun 23;101(7):789-800
10892749
Biophys J. 2000 Feb;78(2):785-99
10653791
J Biol Chem. 1999 Dec 3;274(49):34711-8
10574938
J Biol Chem. 2004 Jul 2;279(27):28243-50
15117946