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Bickers SC, Sayewich JS, Kanelis V. Intrinsically disordered regions regulate the activities of ATP binding cassette transporters. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183202. [PMID: 31972165 DOI: 10.1016/j.bbamem.2020.183202] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/16/2020] [Accepted: 01/17/2020] [Indexed: 12/11/2022]
Abstract
ATP binding cassette (ABC) proteins are a large family of membrane proteins present in all kingdoms of life. These multi-domain proteins are comprised, at minimum, of two membrane-spanning domains (MSD1, MSD2) and two cytosolic nucleotide binding domains (NBD1, NBD2). ATP binding and hydrolysis at the NBDs enables ABC proteins to actively transport solutes across membranes, regulate activities of other proteins, or function as channels. Like most eukaryotic membrane proteins, ABC proteins contain intrinsically disordered regions (IDRs). These conformationally dynamic regions in ABC proteins possess residual structure, are sites of phosphorylation, and mediate protein-protein interactions. Here, we review the role of IDRs in regulating ABC protein activity.
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Affiliation(s)
- Sarah C Bickers
- Department of Chemistry, University of Toronto, Toronto, ON, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Jonathan S Sayewich
- Department of Chemistry, University of Toronto, Toronto, ON, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Voula Kanelis
- Department of Chemistry, University of Toronto, Toronto, ON, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada; Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
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2
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Weiditch SA, Seraphim TV, Houry WA, Kanelis V. Strategies for purification of the bacteriophage HK97 small and large terminase subunits that yield pure and homogeneous samples that are functional. Protein Expr Purif 2019; 160:45-55. [DOI: 10.1016/j.pep.2019.03.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/30/2019] [Accepted: 03/30/2019] [Indexed: 02/06/2023]
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Sooklal CR, López-Alonso JP, Papp N, Kanelis V. Phosphorylation Alters the Residual Structure and Interactions of the Regulatory L1 Linker Connecting NBD1 to the Membrane-Bound Domain in SUR2B. Biochemistry 2018; 57:6278-6292. [PMID: 30273482 DOI: 10.1021/acs.biochem.8b00503] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
ATP-sensitive potassium (KATP) channels in vascular smooth muscle are comprised of four pore-forming Kir6.1 subunits and four copies of the sulfonylurea receptor 2B (SUR2B), which acts as a regulator of channel gating. Recent electron cryo-microscopy (cryo-EM) structures of the pancreatic KATP channel show a central Kir6.2 pore that is surrounded by the SUR1 subunits. Mutations in the L1 linker connecting the first membrane-spanning domain and the first nucleotide binding domain (NBD1) in SUR2B cause cardiac disease; however, this part of the protein is not resolved in the cryo-EM structures. Phosphorylation of the L1 linker, by protein kinase A, disrupts its interactions with NBD1, which increases the MgATP affinity of NBD1 and KATP channel gating. To elucidate the mode by which the L1 linker regulates KATP channels, we have probed the effects of phosphorylation on its structure and interactions using nuclear magnetic resonance (NMR) spectroscopy and other techniques. We demonstrate that the L1 linker is an intrinsically disordered region of SUR2B but possesses residual secondary and compact structure, both of which are disrupted with phosphorylation. NMR binding studies demonstrate that phosphorylation alters the mode by which the L1 linker interacts with NBD1. The data show that L1 linker residues with the greatest α-helical propensity also form the most stable interaction with NBD1, highlighting a hot spot within the L1 linker. This hot spot is the site of disease-causing mutations and is associated with other processes that regulate KATP channel gating. These data provide insights into the mode by which the phospho-regulatory L1 linker regulates KATP channels.
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Affiliation(s)
- Clarissa R Sooklal
- Department of Chemistry , University of Toronto , Toronto , ON , Canada M5S 3H8.,Department of Chemical and Physical Sciences , University of Toronto Mississauga , Mississauga , ON , Canada L5L 1C6
| | - Jorge P López-Alonso
- Department of Chemistry , University of Toronto , Toronto , ON , Canada M5S 3H8.,Department of Chemical and Physical Sciences , University of Toronto Mississauga , Mississauga , ON , Canada L5L 1C6
| | - Natalia Papp
- Department of Chemical and Physical Sciences , University of Toronto Mississauga , Mississauga , ON , Canada L5L 1C6
| | - Voula Kanelis
- Department of Chemistry , University of Toronto , Toronto , ON , Canada M5S 3H8.,Department of Chemical and Physical Sciences , University of Toronto Mississauga , Mississauga , ON , Canada L5L 1C6.,Department of Cell and Systems Biology , University of Toronto , Toronto , ON , Canada M5S 3G5
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4
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Puljung MC. Cryo-electron microscopy structures and progress toward a dynamic understanding of K ATP channels. J Gen Physiol 2018; 150:653-669. [PMID: 29685928 PMCID: PMC5940251 DOI: 10.1085/jgp.201711978] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/26/2018] [Indexed: 12/11/2022] Open
Abstract
Puljung reviews recent cryo-EM KATP channel structures and proposes a mechanism by which ligand binding results in channel opening. Adenosine triphosphate (ATP)–sensitive K+ (KATP) channels are molecular sensors of cell metabolism. These hetero-octameric channels, comprising four inward rectifier K+ channel subunits (Kir6.1 or Kir6.2) and four sulfonylurea receptor (SUR1 or SUR2A/B) subunits, detect metabolic changes via three classes of intracellular adenine nucleotide (ATP/ADP) binding site. One site, located on the Kir subunit, causes inhibition of the channel when ATP or ADP is bound. The other two sites, located on the SUR subunit, excite the channel when bound to Mg nucleotides. In pancreatic β cells, an increase in extracellular glucose causes a change in oxidative metabolism and thus turnover of adenine nucleotides in the cytoplasm. This leads to the closure of KATP channels, which depolarizes the plasma membrane and permits Ca2+ influx and insulin secretion. Many of the molecular details regarding the assembly of the KATP complex, and how changes in nucleotide concentrations affect gating, have recently been uncovered by several single-particle cryo-electron microscopy structures of the pancreatic KATP channel (Kir6.2/SUR1) at near-atomic resolution. Here, the author discusses the detailed picture of excitatory and inhibitory ligand binding to KATP that these structures present and suggests a possible mechanism by which channel activation may proceed from the ligand-binding domains of SUR to the channel pore.
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Affiliation(s)
- Michael C Puljung
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, England, UK
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de Araujo ED, Manaswiyoungkul P, Israelian J, Park J, Yuen K, Farhangi S, Berger-Becvar A, Abu-Jazar L, Gunning PT. High-throughput thermofluor-based assays for inhibitor screening of STAT SH2 domains. J Pharm Biomed Anal 2017; 143:159-167. [DOI: 10.1016/j.jpba.2017.04.052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 04/27/2017] [Accepted: 04/30/2017] [Indexed: 11/24/2022]
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6
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Alvarez CP, Stagljar M, Muhandiram DR, Kanelis V. Hyperinsulinism-Causing Mutations Cause Multiple Molecular Defects in SUR1 NBD1. Biochemistry 2017; 56:2400-2416. [PMID: 28346775 DOI: 10.1021/acs.biochem.6b00681] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The sulfonylurea receptor 1 (SUR1) protein forms the regulatory subunit in ATP sensitive K+ (KATP) channels in the pancreas. SUR proteins are members of the ATP binding cassette (ABC) superfamily of proteins. Binding and hydrolysis of MgATP at the SUR nucleotide binding domains (NBDs) lead to channel opening. Pancreatic KATP channels play an important role in insulin secretion. SUR1 mutations that result in increased levels of channel opening ultimately inhibit insulin secretion and lead to neonatal diabetes. In contrast, SUR1 mutations that disrupt trafficking and/or decrease gating of KATP channels cause congenital hyperinsulinism, where oversecretion of insulin occurs even in the presence of low glucose levels. Here, we present data on the effects of specific congenital hyperinsulinism-causing mutations (G716V, R842G, and K890T) located in different regions of the first nucleotide binding domain (NBD1). Nuclear magnetic resonance (NMR) and fluorescence data indicate that the K890T mutation affects residues throughout NBD1, including residues that bind MgATP, NBD2, and coupling helices. The mutations also decrease the MgATP binding affinity of NBD1. Size exclusion and NMR data indicate that the G716V and R842G mutations cause aggregation of NBD1 in vitro, possibly because of destabilization of the domain. These data describe structural characterization of SUR1 NBD1 and shed light on the underlying molecular basis of mutations that cause congenital hyperinsulinism.
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Affiliation(s)
- Claudia P Alvarez
- Department of Chemical and Physical Sciences, University of Toronto Mississauga , 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6.,Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario, Canada M5S 3H6
| | - Marijana Stagljar
- Department of Chemical and Physical Sciences, University of Toronto Mississauga , 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6.,Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario, Canada M5S 3H6.,Department of Cell and Systems Biology, University of Toronto , 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5
| | - D Ranjith Muhandiram
- Department of Molecular Genetics, University of Toronto , 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Voula Kanelis
- Department of Chemical and Physical Sciences, University of Toronto Mississauga , 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6.,Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario, Canada M5S 3H6.,Department of Cell and Systems Biology, University of Toronto , 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5
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Strategies for over-expression and purification of recombinant full length STAT5B in Escherichia coli. Protein Expr Purif 2017; 129:1-8. [DOI: 10.1016/j.pep.2016.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 08/24/2016] [Accepted: 08/29/2016] [Indexed: 11/21/2022]
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Nelson PT, Jicha GA, Wang WX, Ighodaro E, Artiushin S, Nichols CG, Fardo DW. ABCC9/SUR2 in the brain: Implications for hippocampal sclerosis of aging and a potential therapeutic target. Ageing Res Rev 2015; 24:111-25. [PMID: 26226329 PMCID: PMC4661124 DOI: 10.1016/j.arr.2015.07.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 07/24/2015] [Indexed: 01/06/2023]
Abstract
The ABCC9 gene and its polypeptide product, SUR2, are increasingly implicated in human neurologic disease, including prevalent diseases of the aged brain. SUR2 proteins are a component of the ATP-sensitive potassium ("KATP") channel, a metabolic sensor for stress and/or hypoxia that has been shown to change in aging. The KATP channel also helps regulate the neurovascular unit. Most brain cell types express SUR2, including neurons, astrocytes, oligodendrocytes, microglia, vascular smooth muscle, pericytes, and endothelial cells. Thus it is not surprising that ABCC9 gene variants are associated with risk for human brain diseases. For example, Cantu syndrome is a result of ABCC9 mutations; we discuss neurologic manifestations of this genetic syndrome. More common brain disorders linked to ABCC9 gene variants include hippocampal sclerosis of aging (HS-Aging), sleep disorders, and depression. HS-Aging is a prevalent neurological disease with pathologic features of both neurodegenerative (aberrant TDP-43) and cerebrovascular (arteriolosclerosis) disease. As to potential therapeutic intervention, the human pharmacopeia features both SUR2 agonists and antagonists, so ABCC9/SUR2 may provide a "druggable target", relevant perhaps to both HS-Aging and Alzheimer's disease. We conclude that more work is required to better understand the roles of ABCC9/SUR2 in the human brain during health and disease conditions.
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Affiliation(s)
- Peter T Nelson
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA; University of Kentucky, Department of Pathology, Lexington, KY 40536, USA.
| | - Gregory A Jicha
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA; University of Kentucky, Department of Neurology, Lexington, KY, 40536, USA
| | - Wang-Xia Wang
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA
| | - Eseosa Ighodaro
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA
| | - Sergey Artiushin
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA
| | - Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - David W Fardo
- University of Kentucky, Sanders-Brown Center on Aging, Lexington, KY 40536, USA; Department of Biostatistics, Lexington, KY, 40536, USA
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de Araujo ED, Alvarez CP, López-Alonso JP, Sooklal CR, Stagljar M, Kanelis V. Phosphorylation-dependent changes in nucleotide binding, conformation, and dynamics of the first nucleotide binding domain (NBD1) of the sulfonylurea receptor 2B (SUR2B). J Biol Chem 2015. [PMID: 26198630 DOI: 10.1074/jbc.m114.636233] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The sulfonylurea receptor 2B (SUR2B) forms the regulatory subunit of ATP-sensitive potassium (KATP) channels in vascular smooth muscle. Phosphorylation of the SUR2B nucleotide binding domains (NBD1 and NBD2) by protein kinase A results in increased channel open probability. Here, we investigate the effects of phosphorylation on the structure and nucleotide binding properties of NBD1. Phosphorylation sites in SUR2B NBD1 are located in an N-terminal tail that is disordered. Nuclear magnetic resonance (NMR) data indicate that phosphorylation of the N-terminal tail affects multiple residues in NBD1, including residues in the NBD2-binding site, and results in altered conformation and dynamics of NBD1. NMR spectra of NBD1 lacking the N-terminal tail, NBD1-ΔN, suggest that phosphorylation disrupts interactions of the N-terminal tail with the core of NBD1, a model supported by dynamic light scattering. Increased nucleotide binding of phosphorylated NBD1 and NBD1-ΔN, compared with non-phosphorylated NBD1, suggests that by disrupting the interaction of the NBD core with the N-terminal tail, phosphorylation also exposes the MgATP-binding site on NBD1. These data provide insights into the molecular basis by which phosphorylation of SUR2B NBD1 activates KATP channels.
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Affiliation(s)
- Elvin D de Araujo
- From the Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, the Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, and
| | - Claudia P Alvarez
- From the Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, the Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, and
| | - Jorge P López-Alonso
- From the Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, the Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, and the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Clarissa R Sooklal
- From the Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, the Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, and
| | - Marijana Stagljar
- From the Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, the Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, and the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Voula Kanelis
- From the Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, the Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, and the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
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10
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de Araujo ED, Kanelis V. Successful development and use of a thermodynamic stability screen for optimizing the yield of nucleotide binding domains. Protein Expr Purif 2014; 103:38-47. [PMID: 25153533 DOI: 10.1016/j.pep.2014.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/08/2014] [Accepted: 08/09/2014] [Indexed: 01/09/2023]
Abstract
ATP sensitive potassium (KATP) channels consist of four copies of a pore-forming inward rectifying potassium channel (Kir6.1 or Kir6.2) and four copies of a sulfonylurea receptor (SUR1, SUR2A, or SUR2B). SUR proteins are members of the ATP-binding cassette superfamily of proteins. Binding of ATP to the Kir6.x subunit mediates channel inhibition, whereas MgATP binding and hydrolysis at the SUR NBDs results in channel opening. Mutations in SUR1 and SUR2A NBDs cause diseases of insulin secretion and cardiac disorders, respectively, underlying the importance of studying the NBDs. Although purification of SUR2A NBD1 in a soluble form is possible, the lack of long-term sample stability of the protein in a concentrated form has precluded detailed studies of the protein aimed at gaining a molecular-level understanding of how SUR mutations cause disease. Here we use a convenient and cost-effective thermodynamic screening method to probe stabilizing conditions for SUR2A NBD1. Results from the screen are used to alter the purification protocol to allow for significantly increased yields of the purified protein. In addition, the screen provides strategies for long-term storage of NBD1 and generating NBD1 samples at high concentrations suitable for NMR studies. NMR spectra of NBD1 with MgAMP-PNP are of higher quality compared to using MgATP, indicating that MgAMP-PNP be used as the ligand in future NMR studies. The screen presented here can be expanded to using different additives and can be employed to enhance purification yields, sample life times, and storage of other low stability nucleotide binding domains, such as GTPases.
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Affiliation(s)
- Elvin D de Araujo
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario L5L 1C6, Canada
| | - Voula Kanelis
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario L5L 1C6, Canada; Department of Cell and Systems Biology, University of Toronto, 25 Harbord St., Toronto, Ontario M5S 3G5, Canada.
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Ishii S, Yano T, Okamoto A, Murakawa T, Hayashi H. Boundary of the nucleotide-binding domain of Streptococcus ComA based on functional and structural analysis. Biochemistry 2013; 52:2545-55. [PMID: 23534432 DOI: 10.1021/bi3017069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The ATP-binding cassette (ABC) transporter ComA is a key molecule essential for the first step of the quorum-sensing system of Streptococcus. The nucleotide binding domains (NBD) of Streptococcus mutans ComA with different N termini, NBD1 (amino acid residues 495-760), NBD2 (517-760), and NBD3 (528-760), were expressed, purified, and characterized. The shortest NBD3 corresponds to the region commonly defined as NBD in the database searches of ABC transporters. A kinetic analysis showed that the extra N-terminal region conferred a significantly higher ATP hydrolytic activity on the NBD at a neutral pH. Gel-filtration, X-ray crystallography, and mutational analyses suggest that at least four to five residues beyond the N-terminal boundary of NBD3 indeed participate in stabilizing the protein scaffold of the domain structure, thereby facilitating the ATP-dependent dimerization of NBD which is a prerequisite to the catalysis. These findings, together with the presence of a highly conserved glycine residue in this region, support the redefinition of the N-terminal boundary of the NBD of these types of ABC exporters.
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Affiliation(s)
- Seiji Ishii
- Department of Biochemistry, Faculty of Nursing, Osaka Medical College, Osaka 569-8686, Japan.
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López-Alonso JP, de Araujo ED, Kanelis V. NMR and fluorescence studies of drug binding to the first nucleotide binding domain of SUR2A. Biochemistry 2012; 51:9211-22. [PMID: 23078514 DOI: 10.1021/bi301019e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
ATP sensitive potassium (K(ATP)) channels are composed of four copies of a pore-forming inward rectifying potassium channel (Kir6.1 or Kir6.2) and four copies of a sulfonylurea receptor (SUR1, SUR2A, or SUR2B) that surround the pore. SUR proteins are members of the ATP-binding cassette (ABC) superfamily of proteins. Binding of MgATP at the SUR nucleotide binding domains (NBDs) results in NBD dimerization, and hydrolysis of MgATP at the NBDs leads to channel opening. The SUR proteins also mediate interactions with K(ATP) channel openers (KCOs) that activate the channel, with KCO binding and/or activation involving residues in the transmembrane helices and cytoplasmic loops of the SUR proteins. Because the cytoplasmic loops make extensive interactions with the NBDs, we hypothesized that the NBDs may also be involved in KCO binding. Here, we report nuclear magnetic resonance (NMR) spectroscopy studies that demonstrate a specific interaction of the KCO pinacidil with the first nucleotide binding domain (NBD1) from SUR2A, the regulatory SUR protein in cardiac K(ATP) channels. Intrinsic tryptophan fluorescence titrations also demonstrate binding of pinacidil to SUR2A NBD1, and fluorescent nucleotide binding studies show that pinacidil binding increases the affinity of SUR2A NBD1 for ATP. In contrast, the KCO diazoxide does not interact with SUR2A NBD1 under the same conditions. NMR relaxation experiments and size exclusion chromatography indicate that SUR2A NBD1 is monomeric under the conditions used in drug binding studies. These studies identify additional binding sites for commonly used KCOs and provide a foundation for testing binding of drugs to the SUR NBDs.
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Affiliation(s)
- Jorge P López-Alonso
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6
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