Cryo-EM structure of a nanobody-bound heliorhodopsin

Heliorhodopsins (HeRs) represent a distinct class of microbial rhodopsins (MRs) with an inverted membrane topology compared to other MRs. Previous structural studies have shown that HeRs lack a proton acceptor residue, and protons are never released from the protein. In this study, we present the cr...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2025-01, Vol.750, p.151398, Article 151398
Main Authors: Xia, Ruixue, Sun, Mingxia, Lu, Yang, Wang, Na, Zhang, Anqi, Guo, Changyou, Xu, Zhenmei, Cai, Xuehui, He, Yuanzheng
Format: Article
Language:English
Subjects:
acetate
cryo-EM
Heliorhodopsin
nanobody
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Summary:Heliorhodopsins (HeRs) represent a distinct class of microbial rhodopsins (MRs) with an inverted membrane topology compared to other MRs. Previous structural studies have shown that HeRs lack a proton acceptor residue, and protons are never released from the protein. In this study, we present the cryo-electron microscopy (cryo-EM) structure of HeR bound to a nanobody. The structure reveals an acetate-like molecule in the Schiff base cavity (SBC) on the intracellular side of HeR under neutral condition. Structural comparisons and analyses suggest that the acetate molecule may function as a proton acceptor for the protonated retinal Schiff base (RSB) and act as a mediator for the intramolecular signaling transduction in HeR during light stimulation. These structural insights shed new light on the mechanism and function of HeR. •cryo-EM structure of HeR bound with nanobody•Identification of an acetate molecule in the SBC of HeR under neutral condition•The acetate molecule acts as a mediator for the intramolecular signaling transduction in HeR
ISSN:0006-291X
1090-2104
1090-2104
DOI:10.1016/j.bbrc.2025.151398