Key determinants of the dual clamp/activator function of Complexin.

Autor:	Makke M; Center for Integrative Physiology and Molecular Medicine, School of Medicine, University of Saarland, Homburg, Germany., Pastor-Ruiz A; Center for Integrative Physiology and Molecular Medicine, School of Medicine, University of Saarland, Homburg, Germany., Yarzagaray A; Center for Integrative Physiology and Molecular Medicine, School of Medicine, University of Saarland, Homburg, Germany., Gaya S; Center for Integrative Physiology and Molecular Medicine, School of Medicine, University of Saarland, Homburg, Germany., Zimmer M; Center for Integrative Physiology and Molecular Medicine, School of Medicine, University of Saarland, Homburg, Germany., Frisch W; Center for Integrative Physiology and Molecular Medicine, School of Medicine, University of Saarland, Homburg, Germany., Bruns D; Center for Integrative Physiology and Molecular Medicine, School of Medicine, University of Saarland, Homburg, Germany.
Jazyk:	angličtina
Zdroj:	ELife [Elife] 2024 Nov 25; Vol. 12. Date of Electronic Publication: 2024 Nov 25.
DOI:	10.7554/eLife.92438
Abstrakt:	Complexin determines magnitude and kinetics of synchronized secretion, but the underlying molecular mechanisms remained unclear. Here, we show that the hydrophobic face of the amphipathic helix at the C-terminus of Complexin II (CpxII, amino acids 115-134) binds to fusion-promoting SNARE proteins, prevents premature secretion, and allows vesicles to accumulate in a release-ready state in mouse chromaffin cells. Specifically, we demonstrate that an unrelated amphipathic helix functionally substitutes for the C-terminal domain (CTD) of CpxII and that amino acid substitutions on the hydrophobic side compromise the arrest of the pre-fusion intermediate. To facilitate synchronous vesicle fusion, the N-terminal domain (NTD) of CpxII (amino acids 1-27) specifically cooperates with synaptotagmin I (SytI), but not with synaptotagmin VII. Expression of CpxII rescues the slow release kinetics of the Ca 2+ -binding mutant Syt I R233Q, whereas the N-terminally truncated variant of CpxII further delays it. These results indicate that the CpxII NTD regulates mechanisms which are governed by the forward rate of Ca 2+ binding to Syt I. Overall, our results shed new light on key molecular properties of CpxII that hinder premature exocytosis and accelerate synchronous exocytosis. Competing Interests: MM, AP, AY, SG, MZ, WF, DB No competing interests declared (© 2023, Makke et al.)
Databáze:	MEDLINE
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