title: Gating of human ClC-2 chloride channels and regulation by carboxy-terminal domains.
abstract: Eukaryotic ClC channels are dimeric proteins with each subunit forming an individual protopore. Single protopores are gated by a fast gate, whereas the slow gate is assumed to control both protopores through a cooperative movement of the two carboxy-terminal domains. We here study the role of the carboxy-terminal domain in modulating fast and slow gating of human ClC-2 channels, a ubiquitously expressed ClC-type chloride channel involved in transepithelial solute transport and in neuronal chloride homeostasis. Partial truncation of the carboxy-terminus abolishes function of ClC-2 by locking the channel in a closed position. However, unlike other isoforms, its complete removal preserves function of ClC-2. ClC-2 channels without the carboxy-terminus exhibit fast and slow gates that activate and deactivate significantly faster than in WT channels. In contrast to the prevalent view, a single carboxy-terminus suffices for normal slow gating, whereas both domains regulate fast gating of individual protopores. Our findings demonstrate that the carboxy-terminus is not strictly required for slow gating and that the cooperative gating resides in other regions of the channel protein. ClC-2 is expressed in neurons and believed to open at negative potentials and increased internal chloride concentrations after intense synaptic activity. We propose that the function of the ClC-2 carboxy-terminus is to slow down the time course of channel activation in order to stabilize neuronal excitability.
authors.affiliation: Institut für Neurophysiologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Jennie
authors.initials: J
authors.lastname: Garcia-Olivares
authors.forename: Alexi
authors.initials: A
authors.lastname: Alekov
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Boroumand
authors.forename: Birgit
authors.initials: B
authors.lastname: Begemann
authors.forename: Patricia
authors.initials: P
authors.lastname: Hidalgo
authors.forename: Christoph
authors.initials: C
authors.lastname: Fahlke
mesh_terms: D001665:Binding Sites; D000090007:CLC-2 Chloride Channels; D002460:Cell Line; D018118:Chloride Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003541:Cystathionine beta-Synthase / Q000737:chemistry; D019281:Dimerization; D006801:Humans; D015640:Ion Channel Gating; D007700:Kinetics; D008954:Models, Biological; D016296:Mutagenesis; D009474:Neurons / Q000378:metabolism; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion
chemical_list: D000090007:CLC-2 Chloride Channels; D018118:Chloride Channels; D011993:Recombinant Fusion Proteins; D003541:Cystathionine beta-Synthase
references.citation: Biochem J. 2006 Apr 1;395(1):89-97
references.pmid: 16321142
references.citation: J Gen Physiol. 2001 Jul;118(1):23-32
references.pmid: 11429442
references.citation: Physiol Rev. 2002 Apr;82(2):503-68
references.pmid: 11917096
references.citation: Biochem J. 2006 Jun 15;396(3):449-60
references.pmid: 16526942
references.citation: Nat Struct Mol Biol. 2006 Dec;13(12):1115-9
references.pmid: 17115052
references.citation: Nat Struct Mol Biol. 2007 Jan;14(1):60-7
references.pmid: 17195847
references.citation: Structure. 2007 Jun;15(6):715-25
references.pmid: 17562318
references.citation: J Biol Chem. 2007 Nov 30;282(48):34719-26
references.pmid: 17908688
references.citation: Hum Mutat. 2009 Mar;30(3):397-405
references.pmid: 19191339
references.citation: J Physiol. 2002 May 15;541(Pt 1):103-12
references.pmid: 12015423
references.citation: J Gen Physiol. 2003 Feb;121(2):149-61
references.pmid: 12566541
references.citation: Nat Genet. 2003 Apr;33(4):527-32
references.pmid: 12612585
references.citation: Biophys J. 2003 Apr;84(4):2306-18
references.pmid: 12668439
references.citation: Science. 2003 Apr 4;300(5616):108-12
references.pmid: 12649487
references.citation: Biochem Biophys Res Commun. 2003 Oct 17;310(2):600-5
references.pmid: 14521953
references.citation: Am J Physiol Cell Physiol. 2004 Jan;286(1):C79-89
references.pmid: 13679301
references.citation: J Physiol. 2003 Dec 15;553(Pt 3):873-9
references.pmid: 14617675
references.citation: J Physiol. 2004 Mar 16;555(Pt 3):671-82
references.pmid: 14724195
references.citation: J Biol Chem. 2004 Mar 26;279(13):13140-7
references.pmid: 14718533
references.citation: Biophys J. 2005 Sep;89(3):1710-20
references.pmid: 15980168
references.citation: J Gen Physiol. 2005 Dec;126(6):591-603
references.pmid: 16286506
references.citation: Proc Natl Acad Sci U S A. 2005 Dec 27;102(52):19214-8
references.pmid: 16365297
references.citation: Structure. 2006 Feb;14(2):299-307
references.pmid: 16472749
references.citation: J Biol Chem. 2001 Jan 26;276(4):2347-53
references.pmid: 11035003
references.citation: Gastroenterology. 2004 Apr;126(4):1104-14
references.pmid: 15057749
references.citation: J Physiol. 2004 Jun 1;557(Pt 2):363-78
references.pmid: 14724190
references.citation: J Physiol. 1980 Oct;307:97-129
references.pmid: 6259340
references.citation: Nature. 1992 Mar 5;356(6364):57-60
references.pmid: 1311421
references.citation: Nature. 1995 Feb 9;373(6514):527-31
references.pmid: 7845466
references.citation: Hum Mol Genet. 1995 Mar;4(3):407-13
references.pmid: 7795595
references.citation: Nature. 1996 Sep 26;383(6598):340-3
references.pmid: 8848047
references.citation: J Membr Biol. 1998 May 15;163(2):87-95
references.pmid: 9592073
references.citation: J Biol Chem. 1998 Jun 12;273(24):15110-8
references.pmid: 9614122
references.citation: J Gen Physiol. 1998 Dec;112(6):651-63
references.pmid: 9834138
references.citation: J Gen Physiol. 1998 Dec;112(6):715-26
references.pmid: 9834141
references.citation: J Gen Physiol. 1999 Jul;114(1):1-12
references.pmid: 10398688
references.citation: J Gen Physiol. 1997 Jan;109(1):105-16
references.pmid: 8997669
references.citation: J Biol Chem. 1998 Feb 20;273(8):4304-7
references.pmid: 9468477
references.citation: Biochemistry. 1998 Feb 3;37(5):1315-21
references.pmid: 9477958
references.citation: Am J Physiol. 1998 Apr;274(4 Pt 1):C966-73
references.pmid: 9575793
references.citation: Neuron. 1996 Sep;17(3):543-51
references.pmid: 8816717
references.citation: Proc Natl Acad Sci U S A. 1996 Oct 1;93(20):11248-52
references.pmid: 8855341
references.citation: J Gen Physiol. 1996 Oct;108(4):237-50
references.pmid: 8894974
references.citation: J Physiol. 1996 Dec 1;497 ( Pt 2):423-35
references.pmid: 8961185
references.citation: J Gen Physiol. 1997 Jan;109(1):93-104
references.pmid: 8997668