Mutations of single residues in the complexin N-terminus exhibit distinct phenotypes in synaptic vesicle fusion

• Verfasst von: Toulme, Estelle [VerfasserIn]
• Verfasst von: Murach, Jacqueline Isabell [VerfasserIn]
• Verfasst von: Bärfuss, Simon [VerfasserIn]
• Verfasst von: Kroll, Jana [VerfasserIn]
• Verfasst von: Malsam, Jörg [VerfasserIn]
• Verfasst von: Trimbuch, Thorsten [VerfasserIn]
• Verfasst von: Herman, Melissa A. [VerfasserIn]
• Verfasst von: Söllner, Thomas [VerfasserIn]
• Verfasst von: Rosenmund, Christian [VerfasserIn]
• Titel: Mutations of single residues in the complexin N-terminus exhibit distinct phenotypes in synaptic vesicle fusion
• Verf.angabe: Estelle Toulme, Jacqueline Murach, Simon Bärfuss, Jana Kroll, Jörg Malsam, Thorsten Trimbuch, Melissa A. Herman, Thomas H. Söllner, and Christian Rosenmund
• E-Jahr: 2024
• Jahr: July 31, 2024
• Umfang: 16 S.
• Illustrationen: Illustrationen
• Fussnoten: Erstveröffentlichung: 1. Juli 2024, Artikelversion: 31. Juli 2024 ; Gesehen am 14.07.2025
• Titel Quelle: Enthalten in: The journal of neuroscience
• Ort Quelle: Washington, DC : Soc., 1981
• Jahr Quelle: 2024
• Band/Heft Quelle: 44(2024), 31 vom: Juli, Artikel-ID e0076242024, Seite 1-16
• ISSN Quelle: 1529-2401
• DOI: doi:10.1523/JNEUROSCI.0076-24.2024
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: autaptic neuron
• Sach-SW: complexin
• Sach-SW: mutagenesis
• Sach-SW: readily releasable pool
• Sach-SW: synaptic transmission
• Sach-SW: synaptic vesicles
• K10plus-PPN: 193042521X

Abstract

The release of neurotransmitters (NTs) at central synapses is dependent on a cascade of protein interactions, specific to the presynaptic compartment. Among those dedicated molecules, the cytosolic complexins play an incompletely defined role as synaptic transmission regulators. Complexins are multidomain proteins that bind soluble N-ethylmaleimide sensitive factor attachment protein receptor complexes, conferring both inhibitory and stimulatory functions. Using systematic mutagenesis and comparing reconstituted in vitro membrane fusion assays with electrophysiology in cultured neurons from mice of either sex, we deciphered the function of the N-terminus of complexin (Cpx) II. The N-terminus (amino acid 1-27) starts with a region enriched in hydrophobic amino acids (1-12), which binds lipids. Mutants maintaining this hydrophobic character retained the stimulatory function of Cpx, whereas exchanges introducing charged residues perturbed both spontaneous and evoked exocytosis. Mutants in the more distal region of the N-terminal domain (amino acid 11-18) showed a spectrum of effects. On the one hand, mutation of residue A12 increased spontaneous release without affecting evoked release. On the other hand, replacing D15 with amino acids of different shapes or hydrophobic properties (but not charge) not only increased spontaneous release but also impaired evoked release. Most surprising, this substitution reduced the size of the readily releasable pool, a novel function for Cpx at mammalian synapses. Thus, the exact amino acid composition of the Cpx N-terminus fine-tunes the degree of spontaneous and evoked NT release.