Dynamics of Membrane-Bound G12V-KRAS from Simulations and Single-Molecule FRET in Native Nanodiscs

Biophys J. 2019 Jan 22;116(2):179-183. doi: 10.1016/j.bpj.2018.12.011. Epub 2018 Dec 20.


Recent studies have shown that the small GTPase KRAS adopts multiple orientations with respect to the plane of anionic model membranes, whereby either the three C-terminal helices or the three N-terminal β-strands of the catalytic domain face the membrane. This has functional implications because, in the latter, the membrane occludes the effector-interacting surface. However, it remained unclear how membrane reorientation occurs and, critically, whether it occurs in the cell in which KRAS operates as a molecular switch in signaling pathways. Herein, using data from a 20 μs-long atomistic molecular dynamics simulation of the oncogenic G12V-KRAS mutant in a phosphatidylcholine/phosphatidylserine bilayer, we first show that internal conformational fluctuations of flexible regions in KRAS result in three distinct membrane orientations. We then show, using single-molecule fluorescence resonance energy transfer measurements in native lipid nanodiscs derived from baby hamster kidney cells, that G12V-KRAS samples three conformational states that correspond to the predicted orientations. The combined results suggest that relatively small energy barriers separate orientation states and that signaling-competent conformations dominate the overall population.

Publication types

  • Letter
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cricetinae
  • Cricetulus
  • Fluorescence Resonance Energy Transfer
  • Lipid Bilayers / chemistry*
  • Molecular Dynamics Simulation*
  • Mutation, Missense
  • Nanostructures / chemistry
  • Phosphatidylcholines / chemistry
  • Phosphatidylserines / chemistry
  • Proto-Oncogene Proteins p21(ras) / chemistry*
  • Proto-Oncogene Proteins p21(ras) / genetics
  • Single Molecule Imaging


  • Lipid Bilayers
  • Phosphatidylcholines
  • Phosphatidylserines
  • Proto-Oncogene Proteins p21(ras)