Dynamic behavior of fully solvated beta2-adrenergic receptor, embedded in the membrane with bound agonist or antagonist.
Recently we predicted the 3D structure of the human beta2-adrenergic receptor (beta2AR) and of the binding site of several agonists and antagonists to beta2AR. These predictions (MembStruk and HierDock) included no explicit water and only a few lipid molecules. Here we include explicit H(2)O and an infinite lipid bilayer membrane in molecular dynamics (MD) simulations of three systems: apo-beta2AR, epinephrine-bound beta2AR, and butoxamine-bound beta2AR (epinephrine is an endogenous agonist, and butoxamine is a beta2AR selective antagonist). The predicted structures for apo-beta2AR and butoxamine-beta2AR are stable in MD, but in epinephrine-beta2AR, extracellular water trickles into the binding pocket to mediate hydrogen bonding between the catechol of epinephrine and Ser-204 on helix 5. The epinephrine-beta2AR structure shows dynamic flexibility with small, piston-like movements of helices 3 and 6 and transient interhelical hydrogen bonding between Ser-165 on transmembrane 4 and Ser-207 on transmembrane 5. These couplings and motions may play a role in protein activation. The apo-beta2AR shows less dynamic flexibility, whereas the antagonist-beta2AR structure is quite rigid. This MD validation of the structure predictions for G protein-coupled receptors in explicit lipid and water suggests that these methods can be trusted for studying the mechanism of activation and the design of subtype-specific agonists and antagonists.
Spijker
Peter
P
Materials and Process Simulation Center, MC 74-139, California Institute of Technology, Pasadena, CA 91125, USA.
Vaidehi
Nagarajan
N
Freddolino
Lydia
L
Hilbers
Peter A J
PA
Goddard
William A
WA
D058666:Adrenergic beta-2 Receptor Agonists; D058672:Adrenergic beta-2 Receptor Antagonists; D001059:Apoproteins / Q000737:chemistry / Q000378:metabolism; D001692:Biological Transport; D002078:Butoxamine / Q000737:chemistry / Q000378:metabolism; D003198:Computer Simulation; D004837:Epinephrine / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006860:Hydrogen Bonding; D008024:Ligands; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry* / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D058666:Adrenergic beta-2 Receptor Agonists; D058672:Adrenergic beta-2 Receptor Antagonists; D001059:Apoproteins; D008024:Ligands; D008051:Lipid Bilayers; D018343:Receptors, Adrenergic, beta-2; D012997:Solvents; D014867:Water; D002078:Butoxamine; D004837:Epinephrine