Wuensch, B. | bioRxiv Science

bioRxiv2026

Modulation of the agonist and antagonist activity of peptidic FPR1 ligands through N-terminal modifications: A structural and functional analysis

Formyl peptide receptor 1 (FPR1) is a promising therapeutic target for the treatment of inflammatory and infectious diseases. Although multiple classes of peptides are known to modulate FPR1 activity, comprehensive studies systematically linking N-terminal modifications to binding, mechanism of action and functional outcomes remain limited. In this study, we aimed to rationalise the binding and activity of three peptide series (MLF, FLFLF, and MLFYLA) featuring diverse N-terminal modifications from a structural point of view. A combined in silico and in vitro approach was employed to evaluate the activity of newly designed peptide agonists and to generate mechanistic binding hypotheses. Our findings led to the identification of a transmembrane binding pocket in FPR1, which provides a structural basis for the observed antagonist and partial agonist behaviours and leads to a generalisable strategy for tuning the functional outcome of peptidic ligands.

pharmacology and toxicology↗

bioRxiv2021

An Activator Locks Kv7.1 Channels Open by Electro-Mechanical Uncoupling and Allosterically Modulates its Pore with similarity to phosphatidylinositol-4,5-bisphosphat

Loss-of-function mutations in Kv7.1 often lead to long QT syndrome (LQTS), a cardiac repolarization disorder associated with increased risk of arrhythmia and subsequent sudden cardiac death. The discovery of agonistic IKs modulators may offer a new potential strategy in pharmacological treatment of this disorder. The benzodiazepine (R)-L3 potently activates Kv7.1 channels and shortens action potential duration, thus may represent a starting point for drug development. However, the molecular mechanisms underlying modulation by (R)-L3 are still unknown. By combining alanine scanning mutagenesis, non-canonical amino acid incorporation, voltage-clamp electrophysiology and fluorometry, and in silico protein modelling, we showed that (R)-L3 not only stimulates currents by allosteric modulation of the pore domain but also alters the kinetics independently from the pore domain effects. We identified novel (R)-L3-interacting key residues in the lower S4-segment of Kv7.1 and observed an uncoupling of the outer S4 segment with the inner S5, S6 and selectivity filter segments. Summarizing, we provide structural and functional evidence for two independent Kv7.1 activating mechanisms by a single modulator.

biophysics↗