Point mutations in the pore region directly or indirectly affect glibenclamide block of the CFTR chloride channel

被引:24
作者
Gupta, J [1 ]
Linsdell, P [1 ]
机构
[1] Dalhousie Univ, Dept Physiol & Biophys, Halifax, NS B3H 4H7, Canada
来源
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY | 2002年 / 443卷 / 5-6期
关键词
blocker binding; CFTR; chloride channel; cystic fibrosis; multi-ion pore; open channel block; sulfonylurea;
D O I
10.1007/s00424-001-0762-0
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
The sulfonylurea glibenclamide is a relatively potent inhibitor of the CFTR Cl- channel. This inhibition is thought to be via an open channel block mechanism. However, nothing is known about the physical nature of the glibenclamide-binding site on CFTR. Here we show that mutations in the pore-forming 6th and 12th transmembrane regions of CFTR affect block by intracellular glibenclamide, confirming previous suggestions that glibenclamide enters the pore in order to block the channel. Two mutations in the 6th transmembrane region, F337A and T338A. significantly weakened glibenclamide block, consistent with a direct interaction between glibenclamide and this region of the pore. Interestingly, two mutations in the 12th transmembrane region (N1138A and T1142A) significantly strengthened block. These two mutations also abolished the dependence of block on the extracellular Cl- concentration, which in wild-type CFTR suggests an interaction between Cl- and glibenclamide within the channel pore that limits block. We suggest that mutations in the 12th transmembrane region strengthen glibenclamide block not by directly altering interactions between glibenclamide and the pore walls, but indirectly by reducing interactions between Cl- ions and glibenclamide within the pore. This work demonstrates that glibenclamide binds within the CFTR channel pore and begins to define its intrapore binding site.
引用
收藏
页码:739 / 747
页数:9
相关论文
共 45 条
[1]   THE SULFONYLUREA RECEPTOR [J].
ASHCROFT, SJH ;
ASHCROFT, FM .
BIOCHIMICA ET BIOPHYSICA ACTA, 1992, 1175 (01) :45-49
[2]   Identification of the high-affinity tolbutamide site on the SUR1 subunit of the KATP channel [J].
Ashfield, R ;
Gribble, FM ;
Ashcroft, SJH ;
Ashcroft, FM .
DIABETES, 1999, 48 (06) :1341-1347
[3]   The tolbutamide site of SUR1 and a mechanism for its functional coupling to KATP channel closure [J].
Babenko, AP ;
Gonzalez, G ;
Bryan, J .
FEBS LETTERS, 1999, 459 (03) :367-376
[4]   Sulfonylurea receptors:: ABC transporters that regulate ATP-sensitive K+ channels [J].
Bryan, J ;
Aguilar-Bryan, Z .
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES, 1999, 1461 (02) :285-303
[5]   Inhibition of heterologously expressed cystic fibrosis transmembrane conductance regulator Cl- channels by non-sulphonylurea hypoglycaemic agents [J].
Cai, Z ;
Lansdell, KA ;
Sheppard, DN .
BRITISH JOURNAL OF PHARMACOLOGY, 1999, 128 (01) :108-118
[6]   Identification of cystic fibrosis transmembrane conductance regulator channel-lining residues in and flanking the M6 membrane-spanning segment [J].
Cheung, M ;
Akabas, MH .
BIOPHYSICAL JOURNAL, 1996, 70 (06) :2688-2695
[7]   Cystic fibrosis-associated mutations at arginine 347 alter the pore architecture of CFTR - Evidence for disruption of a salt bridge [J].
Cotten, JF ;
Welsh, MJ .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1999, 274 (09) :5429-5435
[8]  
Dawson David C., 1999, Physiological Reviews, V79, pS47
[9]   The human ATP-binding cassette (ABC) transporter superfamily [J].
Dean, M ;
Rzhetsky, A ;
Allikmets, R .
GENOME RESEARCH, 2001, 11 (07) :1156-1166
[10]   Asymmetric structure of the cystic fibrosis transmembrane conductance regulator chloride channel pore suggested by mutagenesis of the twelfth transmembrane region [J].
Gupta, J ;
Evagelidis, A ;
Hanrahan, JW ;
Linsdell, P .
BIOCHEMISTRY, 2001, 40 (22) :6620-6627