Structural basis of closed groove scrambling by a TMEM16 protein.

Autor:	Feng Z; Department of Anesthesiology, Weill Cornell Medical College., Alvarenga OE; Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Medical College., Accardi A; Department of Anesthesiology, Weill Cornell Medical College.; Department of Physiology and Biophysics, Weill Cornell Medical College.; Department of Biochemistry, Weill Cornell Medical College.
Jazyk:	angličtina
Zdroj:	BioRxiv : the preprint server for biology [bioRxiv] 2024 Jan 30. Date of Electronic Publication: 2024 Jan 30.
DOI:	10.1101/2023.08.11.553029
Abstrakt:	Activation of Ca 2+ -dependent TMEM16 scramblases induces the externalization of phosphatidylserine, a key molecule in multiple signaling processes. Current models suggest that the TMEM16s scramble lipids by deforming the membrane near a hydrophilic groove, and that Ca 2+ dependence arises from the different association of lipids with an open or closed groove. However, the molecular rearrangements involved in groove opening and of how lipids reorganize outside the closed groove remain unknown. Using cryogenic electron microscopy, we directly visualize how lipids associate at the closed groove of Ca 2+ -bound nhTMEM16 in nanodiscs. Functional experiments pinpoint the lipid-protein interaction sites critical for closed groove scrambling. Structural and functional analyses suggest groove opening entails the sequential appearance of two π-helical turns in the groove-lining TM6 helix and identify critical rearrangements. Finally, we show that the choice of scaffold protein and lipids affects the conformations of nhTMEM16 and their distribution, highlighting a key role of these factors in cryoEM structure determination. Competing Interests: Competing Interests statement The authors declare no competing interests.
Databáze:	MEDLINE
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