How Photoswitchable Lipids Affect the Order and Dynamics of Lipid Bilayers and Embedded Proteins

Creators: Doroudgar, Mahmoudreza; Morstein, Johannes¹; Becker-Baldus, Johanna; Trauner, Dirk; Glaubitz, Clemens

1. New York University

Abstract

Altering the properties of phospholipid membranes by light is an attractive option for the noninvasive manipulation of membrane proteins and cellular functions. Lipids with an azobenzene group within their acyl chains such as AzoPC are suitable tools for manipulating lipid order and dynamics through a light-induced trans-to-cis isomerization. However, the action of these photoswitchable lipids at the atomic level is still poorly understood. Here, liposomes containing AzoPC, POPE, and POPG have been characterized by solid-state NMR through chemical shift and dipolar CH order parameter measurements. Upon UV-light illumination, an efficient trans-to-cis conversion can be achieved resulting in a localized reduction of the CH order parameter within the bulk lipid acyl chains. This effect is even more pronounced in liposomes containing the integral membrane protein E. coli diacylglycerol kinase. The protein responds to the light-induced trans-to-cis isomerization by a site-specific increase in the molecular dynamics as observed by altered cross peak intensities in NCA spectra. This study represents a proof-of-concept demonstration for the use of photoswitchable lipids to modulate membrane properties by light for inducing dynamic changes within an embedded membrane protein.

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Acknowledgement

This work was supported by the Deutsche Forschungsgemeinschaft Graduate School CLiC (Complex Light Control, GRK 1986).

Additional Information

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.1c03524.

¹H-NOESY MAS spectrum on AzoPC phenyl ring region (Figure S1); 2D R-PDLF spectra and order parameter profile of POPE/POPG (Figure S2); Monitoring photoconversion of proteo-photoliposomes by ¹H MAS NMR (Figure S3); 2D R-PDLF spectra of proteo-photoliposomes (LPR 50) (Figure S4); Slices from 2D NCA spectra of DgkA (Figure S5); NCA cross peak intensity changes mapped onto the DgkA 3D structure (Figure S6); ¹H NOESY MAS spectra of photoliposomes (Figure S7); ¹H NOESY MAS spectra of proteo-photoliposomes (Figure S8); Normalization of NOESY cross peak intensities (Figure S9); Dipolar spectra for carbons 9′, 10′ extracted from R-PDLF spectra (Figure S10); Phase transition of photoliposomes monitored by ¹H MAS NMR (Figure S11); Dipolar couplings and calculated order parameters (Tables S1–S7); Experimental parameters (Table S8) (PDF)

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