cAMP-dependent protein kinase phosphorylation produces interdomain movement in SUR2B leading to activation of the vascular KATP channel.
Vascular ATP-sensitive K(+) channels are activated by multiple vasodilating hormones and neurotransmitters via PKA. A critical PKA phosphorylation site (Ser-1387) is found in the second nucleotide-binding domain (NBD(2)) of the SUR2B subunit. To understand how phosphorylation at Ser-1387 leads to changes in channel activity, we modeled the SUR2B using a newly crystallized ABC protein SAV1866. The model showed that Ser-1387 was located on the interface of NBD2 with TMD1 and physically interacted with Tyr-506 in TMD1. A positively charged residue (Arg-1462) in NBD2 was revealed in the close vicinity of Ser-1387. Mutation of either of these three residues abolished PKA-dependent channel activation. Molecular dynamics simulations suggested that Ser-1387, Tyr-506, and Arg-1462 formed a compact triad upon Ser-1387 phosphorylation, leading to reshaping of the NBD2 interface and movements of NBD2 and TMD1. Restriction of the interdomain movements by engineering a disulfide bond between TMD1 and NBD2 prevented the channel activation in a redox-dependent manner. Thus, a channel-gating mechanism is suggested through enhancing the NBD-TMD coupling efficiency following Ser-1387 phosphorylation, which is shared by multiple vasodilators.
Shi
Yun
Y
Department of Biology, Georgia State University, Atlanta, Georgia 30302-4010, USA.
Chen
Xianfeng
X
Wu
Zhongying
Z
Shi
Weiwei
W
Yang
Yang
Y
Cui
Ningren
N
Jiang
Chun
C
Harrison
Robert W
RW
D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D054086:KATP Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009131:Muscle, Smooth, Vascular / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D010766:Phosphorylation; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D011955:Receptors, Drug / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D064233:Sulfonylurea Receptors
D018528:ATP-Binding Cassette Transporters; D004220:Disulfides; D054086:KATP Channels; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D017868:Cyclic AMP-Dependent Protein Kinases