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Rotational and Translational Dynamics of Ras Proteins upon Binding to Model Membrane Systems
Author(s) -
Werkmüller Alexander,
Triola Gemma,
Waldmann Herbert,
Winter Roland
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300617
Subject(s) - chemistry , lipid anchored protein , membrane , biophysics , rotational diffusion , fluorescence anisotropy , membrane protein , dimer , plasma protein binding , biochemistry , molecule , biology , autophagy , apoptosis , organic chemistry
Plasma‐membrane‐associated Ras proteins typically control signal transduction processes. As nanoclustering and membrane viscosity sensing provide plausible signaling mechanisms, determination of the rotational and translational dynamics of membrane‐bound Ras isoforms can help to link their dynamic mobility to their function. Herein, by using time‐resolved fluorescence anisotropy and correlation spectroscopic measurements, we obtain the rotational‐correlation time and the translational diffusion coefficient of lipidated boron‐dipyrromethene‐labeled Ras, both in bulk Ras and upon membrane binding. The results show that the second lipidation motif of N ‐Ras triggers dimer formation in bulk solution, whereas K ‐Ras4B is monomeric. Upon membrane binding, an essentially free rotation of the G ‐domain is observed, along with a high lateral mobility; the latter is essentially limited by the viscosity of the membrane and by lipid‐mediated electrostatic interactions. This high diffusional mobility warrants rapid recognition–binding sequences in the membrane‐bound state, thereby facilitating efficient interactions between the Ras proteins and scaffolding or effector proteins. The lipid‐like rapid lateral diffusion observed here complies with in vivo data.