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Role for SUR2A ED domain in allosteric coupling within the K(ATP) channel complex.

Karger AB, Park S, Reyes S, Bienengraeber M, Dyer RB, Terzic A, Alekseev AE - J. Gen. Physiol. (2008)

Bottom Line: Here, we analyzed the role of the ED domain, a stretch of 15 negatively charged aspartate/glutamate amino acid residues (948-962) of the SUR2A isoform, in the regulation of cardiac K(ATP) channels.Disruption of the ED domain impeded cooperative NBDs interaction and interrupted the regulation of K(ATP) channel complexes by MgADP, potassium channel openers, and sulfonylurea drugs.Thus, the ED domain is a structural component of the allosteric pathway within the K(ATP) channel complex integrating transduction of diverse nucleotide-dependent states in the regulatory SUR subunit to the open/closed states of the K+-conducting channel pore.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA.

ABSTRACT
Allosteric regulation of heteromultimeric ATP-sensitive potassium (K(ATP)) channels is unique among protein systems as it implies transmission of ligand-induced structural adaptation at the regulatory SUR subunit, a member of ATP-binding cassette ABCC family, to the distinct pore-forming K+ (Kir6.x) channel module. Cooperative interaction between nucleotide binding domains (NBDs) of SUR is a prerequisite for K(ATP) channel gating, yet pathways of allosteric intersubunit communication remain uncertain. Here, we analyzed the role of the ED domain, a stretch of 15 negatively charged aspartate/glutamate amino acid residues (948-962) of the SUR2A isoform, in the regulation of cardiac K(ATP) channels. Disruption of the ED domain impeded cooperative NBDs interaction and interrupted the regulation of K(ATP) channel complexes by MgADP, potassium channel openers, and sulfonylurea drugs. Thus, the ED domain is a structural component of the allosteric pathway within the K(ATP) channel complex integrating transduction of diverse nucleotide-dependent states in the regulatory SUR subunit to the open/closed states of the K+-conducting channel pore.

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The ED domain, a candidate for allosteric intersubunit communication. (A) The ED domain in SUR, located in the CL6 downstream of NBD1, consists of 15 linear aspartate and glutamate residues, and structurally overlaps with the R domain in CFTR. (B) The ED domain (in red) of SUR isoforms is not conserved in other ABC proteins. ClustalW software (www.ch.embnet.org) was used to align CL6, a region between TMD1 and TMD2 that includes NBD1, for SUR isoforms, i.e., SUR1(606–1005) and SUR2A (591–987), as well as two representative ABCC family members, MRP1(613–963) and CFTR(351–854). The SUR ED domains are in red, while the PKA-phosphorylated serines in the R domain of CFTR are shaded in blue. While the SUR ED domains are not conserved among ABCC proteins, they match the location of the serine-rich R domain of CFTR. All sequences are from mouse.
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fig1: The ED domain, a candidate for allosteric intersubunit communication. (A) The ED domain in SUR, located in the CL6 downstream of NBD1, consists of 15 linear aspartate and glutamate residues, and structurally overlaps with the R domain in CFTR. (B) The ED domain (in red) of SUR isoforms is not conserved in other ABC proteins. ClustalW software (www.ch.embnet.org) was used to align CL6, a region between TMD1 and TMD2 that includes NBD1, for SUR isoforms, i.e., SUR1(606–1005) and SUR2A (591–987), as well as two representative ABCC family members, MRP1(613–963) and CFTR(351–854). The SUR ED domains are in red, while the PKA-phosphorylated serines in the R domain of CFTR are shaded in blue. While the SUR ED domains are not conserved among ABCC proteins, they match the location of the serine-rich R domain of CFTR. All sequences are from mouse.

Mentions: The present study analyzes an aspartate/glutamate-rich domain as a candidate common transducer securing allosteric regulation in the cardiac KATP channel complex, comprised of Kir6.2 and SUR2A channel isoforms. SUR2A contains a stretch of 15 negatively charged aspartate and glutamate residues, designated the ED domain adjacent to NBD1 within the sixth cytoplasmic loop (Fig. 1 A). The ED domain does not overlap with known binding sites for KATP channel ligands (Aguilar-Bryan et al., 1998; Uhde et al., 1999; Moreau et al., 2000; Mikhailov et al., 2001; Gribble and Reimann, 2003). Sequence alignment revealed that the ED domain is not conserved among ABCC subfamily members (Fig. 1 B), yet it matches the location of the R domain in ABCC7 encoding the CFTR channel (Fig. 1 A), which when phosphorylated permits nucleotide-dependent gating of Cl− conduction (Aguilar-Bryan et al., 1998; Ostedgaard et al., 2001). Thus, the ED domain emerges as a candidate allosteric transducer within KATP channel complexes.


Role for SUR2A ED domain in allosteric coupling within the K(ATP) channel complex.

Karger AB, Park S, Reyes S, Bienengraeber M, Dyer RB, Terzic A, Alekseev AE - J. Gen. Physiol. (2008)

The ED domain, a candidate for allosteric intersubunit communication. (A) The ED domain in SUR, located in the CL6 downstream of NBD1, consists of 15 linear aspartate and glutamate residues, and structurally overlaps with the R domain in CFTR. (B) The ED domain (in red) of SUR isoforms is not conserved in other ABC proteins. ClustalW software (www.ch.embnet.org) was used to align CL6, a region between TMD1 and TMD2 that includes NBD1, for SUR isoforms, i.e., SUR1(606–1005) and SUR2A (591–987), as well as two representative ABCC family members, MRP1(613–963) and CFTR(351–854). The SUR ED domains are in red, while the PKA-phosphorylated serines in the R domain of CFTR are shaded in blue. While the SUR ED domains are not conserved among ABCC proteins, they match the location of the serine-rich R domain of CFTR. All sequences are from mouse.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2248718&req=5

fig1: The ED domain, a candidate for allosteric intersubunit communication. (A) The ED domain in SUR, located in the CL6 downstream of NBD1, consists of 15 linear aspartate and glutamate residues, and structurally overlaps with the R domain in CFTR. (B) The ED domain (in red) of SUR isoforms is not conserved in other ABC proteins. ClustalW software (www.ch.embnet.org) was used to align CL6, a region between TMD1 and TMD2 that includes NBD1, for SUR isoforms, i.e., SUR1(606–1005) and SUR2A (591–987), as well as two representative ABCC family members, MRP1(613–963) and CFTR(351–854). The SUR ED domains are in red, while the PKA-phosphorylated serines in the R domain of CFTR are shaded in blue. While the SUR ED domains are not conserved among ABCC proteins, they match the location of the serine-rich R domain of CFTR. All sequences are from mouse.
Mentions: The present study analyzes an aspartate/glutamate-rich domain as a candidate common transducer securing allosteric regulation in the cardiac KATP channel complex, comprised of Kir6.2 and SUR2A channel isoforms. SUR2A contains a stretch of 15 negatively charged aspartate and glutamate residues, designated the ED domain adjacent to NBD1 within the sixth cytoplasmic loop (Fig. 1 A). The ED domain does not overlap with known binding sites for KATP channel ligands (Aguilar-Bryan et al., 1998; Uhde et al., 1999; Moreau et al., 2000; Mikhailov et al., 2001; Gribble and Reimann, 2003). Sequence alignment revealed that the ED domain is not conserved among ABCC subfamily members (Fig. 1 B), yet it matches the location of the R domain in ABCC7 encoding the CFTR channel (Fig. 1 A), which when phosphorylated permits nucleotide-dependent gating of Cl− conduction (Aguilar-Bryan et al., 1998; Ostedgaard et al., 2001). Thus, the ED domain emerges as a candidate allosteric transducer within KATP channel complexes.

Bottom Line: Here, we analyzed the role of the ED domain, a stretch of 15 negatively charged aspartate/glutamate amino acid residues (948-962) of the SUR2A isoform, in the regulation of cardiac K(ATP) channels.Disruption of the ED domain impeded cooperative NBDs interaction and interrupted the regulation of K(ATP) channel complexes by MgADP, potassium channel openers, and sulfonylurea drugs.Thus, the ED domain is a structural component of the allosteric pathway within the K(ATP) channel complex integrating transduction of diverse nucleotide-dependent states in the regulatory SUR subunit to the open/closed states of the K+-conducting channel pore.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA.

ABSTRACT
Allosteric regulation of heteromultimeric ATP-sensitive potassium (K(ATP)) channels is unique among protein systems as it implies transmission of ligand-induced structural adaptation at the regulatory SUR subunit, a member of ATP-binding cassette ABCC family, to the distinct pore-forming K+ (Kir6.x) channel module. Cooperative interaction between nucleotide binding domains (NBDs) of SUR is a prerequisite for K(ATP) channel gating, yet pathways of allosteric intersubunit communication remain uncertain. Here, we analyzed the role of the ED domain, a stretch of 15 negatively charged aspartate/glutamate amino acid residues (948-962) of the SUR2A isoform, in the regulation of cardiac K(ATP) channels. Disruption of the ED domain impeded cooperative NBDs interaction and interrupted the regulation of K(ATP) channel complexes by MgADP, potassium channel openers, and sulfonylurea drugs. Thus, the ED domain is a structural component of the allosteric pathway within the K(ATP) channel complex integrating transduction of diverse nucleotide-dependent states in the regulatory SUR subunit to the open/closed states of the K+-conducting channel pore.

Show MeSH
Related in: MedlinePlus