The Molecular Switching Mechanism at the Conserved D(E)RY Motif in Class-A GPCRs.

Journal article
(Original article)


Publication Details

Author(s): Sandoval A, Eichler S, Madathil S, Reeves PJ, Fahmy K, Böckmann R
Journal: Biophysical Journal
Publication year: 2016
Volume: 111
Journal issue: 1
Pages range: 79-89
ISSN: 0006-3495
eISSN: 1542-0086
Language: English


Abstract


The disruption of ionic and H-bond interactions between the cytosolic ends of transmembrane helices TM3 and TM6 of class-A (rhodopsin-like) G protein-coupled receptors (GPCRs) is a hallmark for their activation by chemical or physical stimuli. In the bovine photoreceptor rhodopsin, this is accompanied by proton uptake at Glu(134) in the class-conserved D(E)RY motif. Studies on TM3 model peptides proposed a crucial role of the lipid bilayer in linking protonation to stabilization of an active state-like conformation. However, the molecular details of this linkage could not be resolved and have been addressed in this study by molecular dynamics (MD) simulations on TM3 model peptides in a bilayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). We show that protonation of the conserved glutamic acid alters the peptide insertion depth in the membrane, its side-chain rotamer preferences, and stabilizes the C-terminal helical structure. These factors contribute to the rise of the side-chain pKa (> 6) and to reduced polarity around the TM3 C terminus as confirmed by fluorescence spectroscopy. Helix stabilization requires the protonated carboxyl group; unexpectedly, this stabilization could not be evoked with an amide in MD simulations. Additionally, time-resolved Fourier transform infrared (FTIR) spectroscopy of TM3 model peptides revealed a different kinetics for lipid ester carbonyl hydration, suggesting that the carboxyl is linked to more extended H-bond clusters than an amide. Remarkably, this was seen as well in DOPC-reconstituted Glu(134)- and Gln(134)-containing bovine opsin mutants and demonstrates that the D(E)RY motif is a hydrated microdomain. The function of the D(E)RY motif as a proton switch is suggested to be based on the reorganization of the H-bond network at the membrane interface.



FAU Authors / FAU Editors

Böckmann, Rainer Prof. Dr.
Professur für Computational Biology


Additional Organisation
Graduiertenkolleg 1962 Dynamische Wechselwirkungen an Biologischen Membranen - von Einzelmolekülen zum Gewebe


External institutions
Helmholtz-Zentrum Dresden-Rossendorf (HZDR)
University of Essex
University of Illinois at Urbana-Champaign


How to cite

APA:
Sandoval, A., Eichler, S., Madathil, S., Reeves, P.J., Fahmy, K., & Böckmann, R. (2016). The Molecular Switching Mechanism at the Conserved D(E)RY Motif in Class-A GPCRs. Biophysical Journal, 111(1), 79-89. https://dx.doi.org/10.1016/j.bpj.2016.06.004

MLA:
Sandoval, Angelica, et al. "The Molecular Switching Mechanism at the Conserved D(E)RY Motif in Class-A GPCRs." Biophysical Journal 111.1 (2016): 79-89.

BibTeX: 

Last updated on 2019-17-06 at 09:38