cAMP-dependent protein kinase phosphorylation produces interdomain movement in SUR2B leading to activation of the vascular KATP channel

J Biol Chem. 2008 Mar 21;283(12):7523-30. doi: 10.1074/jbc.M709941200. Epub 2008 Jan 15.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry
  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism*
  • Amino Acid Substitution
  • Animals
  • Cyclic AMP-Dependent Protein Kinases / chemistry
  • Cyclic AMP-Dependent Protein Kinases / genetics
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Disulfides / chemistry
  • Disulfides / metabolism
  • KATP Channels / chemistry
  • KATP Channels / genetics
  • KATP Channels / metabolism*
  • Models, Molecular*
  • Muscle, Smooth, Vascular / chemistry
  • Muscle, Smooth, Vascular / metabolism*
  • Oxidation-Reduction
  • Phosphorylation
  • Potassium Channels / chemistry
  • Potassium Channels / genetics
  • Potassium Channels / metabolism*
  • Potassium Channels, Inwardly Rectifying / chemistry
  • Potassium Channels, Inwardly Rectifying / genetics
  • Potassium Channels, Inwardly Rectifying / metabolism*
  • Protein Structure, Tertiary / physiology
  • Rats
  • Receptors, Drug / chemistry
  • Receptors, Drug / genetics
  • Receptors, Drug / metabolism*
  • Sulfonylurea Receptors

Substances

  • ATP-Binding Cassette Transporters
  • Disulfides
  • KATP Channels
  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • Receptors, Drug
  • Sulfonylurea Receptors
  • Cyclic AMP-Dependent Protein Kinases