Format

Send to

Choose Destination
Biochim Biophys Acta Biomembr. 2019 Oct 28:183113. doi: 10.1016/j.bbamem.2019.183113. [Epub ahead of print]

Membrane matters: The impact of a nanodisc-bilayer or a detergent microenvironment on the properties of two eubacterial rhodopsins.

Author information

1
Department of Biophysical Organic Chemsitry, Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands. Electronic address: S.Ganapathy-1@tudelft.nl.
2
Department of Biophysical Organic Chemsitry, Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands.
3
Department of Physics and Astronomy, VU University Amsterdam, Amsterdam, the Netherlands.
4
Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands.
5
Department of Biophysical Organic Chemsitry, Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands; Department of Biochemistry, Radboud University Medical Center, Nijmegen, the Netherlands. Electronic address: w.j.de.grip@umail.leidenuniv.nl.

Abstract

Multi-spanning membrane proteins usually require solubilization to allow proper purification and characterization, which generally impairs their structural and functional integrity. We have tested the efficacy of several commonly used detergents and membrane-mimicking nanodiscs with respect to solubilization, spectral properties, thermal stability and oligomeric profile of two membrane proteins from the eubacterial rhodopsin family, green proteorhodopsin (PR) and Gloeobacter violaceus rhodopsin (GR). Good solubilization was observed for the detergents TritonX-100 and dodecylphosphocholine (DPC), but DPC in particular strongly affected the thermal stability of PR and especially GR. The least deleterious effects were obtained with n-dodecyl-β-D-maltopyranoside (DDM) and octyl glucose neopentyl glycol (OGNG), which adequately stabilized the native oligomeric and monomeric state of PR and GR, respectively. The transition from the oligomeric to the monomeric state is accompanied by a small red-shift. Both GR and PR were rather unstable in SMA-nanodiscs, but the highest thermal stability was realized by the MSP-nanodisc environment. The size of the MSP-nanodisc was too small to fit the PR hexamer, but large enough to contain the PR monomer and GR trimer. This permitted the comparison of the photocycle of trimeric GR in a membrane-mimicking (MSP-nanodisc) and a detergent (DDM) environment. The ultrarapid early phase of the photocycle (femto- to picosecond lifetimes) showed very similar kinetics in either environment, but the slower part, initiated with proton transfer and generation of the M intermediate, proceeded faster in the nanodisc environment. The implications of our results for the biophysical characterization of PR and GR are discussed.

KEYWORDS:

Detergent micelles; Membrane proteins; Microbial rhodopsins; Nanodisc; Photoresponse; Thermal stability

PMID:
31672539
DOI:
10.1016/j.bbamem.2019.183113
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center