PMID: 30291362

Authors:

Schmidt HR, Betz RM, Dror RO, Kruse AC

Title:

Structural basis for sigma1 receptor ligand recognition.

Journal:

Nat Struct Mol Biol. 2018 Oct;25(10):981-987. doi: 10.1038/s41594-018-0137-2., Epub 2018 Oct 5.

Abstract:

The sigma1 receptor is a poorly understood membrane protein expressed throughout the human body. Ligands targeting the sigma1 receptor are in clinical trials for treatment of Alzheimer's disease, ischemic stroke, and neuropathic pain. However, relatively little is known regarding the sigma1 receptor's molecular function. Here, we present crystal structures of human sigma1 receptor bound to the antagonists haloperidol and NE-100, and the agonist (+)-pentazocine, at crystallographic resolutions of 3.1 A, 2.9 A, and 3.1 A, respectively. These structures reveal a unique binding pose for the agonist. The structures and accompanying molecular dynamics (MD) simulations identify agonist-induced structural rearrangements in the receptor. Additionally, we show that ligand binding to sigma1 is a multistep process that is rate limited by receptor conformational change. We used MD simulations to reconstruct a ligand binding pathway involving two major conformational changes. These data provide a framework for understanding the molecular basis for sigma1 agonism.