Unraveling the key-lock interaction mechanisms of the human neuropeptide Y type 4 receptor (hY4R) via solid-state NMR spectroscopy.

Abstract

Human neuropeptide Y receptors (hYxR) are rhodopsin-like, peptide-binding G-protein coupled receptors (GPCRs). They are expressed within the gut-brain axis network, which allows several possible activation mechanisms, and thus downstream signaling pathways. hYxR therefore regulate a broad spectrum of biological functions (e.g., metabolic balance, vasoconstriction/dilation, circadian rhythm), and also play a central role in the development of several wide-spread pathologies such as several types of cancer, obesity/anorexia, anxiety and depression. Their functions and dysfunctions are tightly dependent on the specific extra- and intracellular coupling partners, as well as on the type of lipid membrane in which they are embedded. Understanding this complex interplay of receptor conformations/bound ligands/lipid environment has received much attention in the biochemical and biophysical communities, especially over the last 20 years, often motivated by the urgent need to develop selective therapeutics, based on receptor-specific lock-key mechanisms. Here, we present our novel approach to the study of conformational dynamics of the human Y receptor subtype 4 (hY4R - the lock), which has received very little attention compared to the rest of the hYxR family. Using cell-free protein expression strategies and solid-state NMR spectroscopy, we characterize structural changes of the receptor at the molecular level, when activated by different endogenous peptide ligands (the keys), namely pancreatic polypeptide (PP) and neuropeptide Y (NPY). This approach has the enormous potential to bringing us one step closer to understanding the specific key-lock interactions, which give rise to particular biological functions, and thus to the development of subtype-specific therapeutics.