Redox-Promoting Protein Motions in Rubredoxin
- ORNL
- Université Montpellier 2, France
- National Institute of Standards and Technology (NIST)
Proteins are dynamic objects, constantly undergoing conformational fluctuations, yet the linkage between internal protein motion and function is widely debated. This manuscript reports on the characterization of temperature-activated collective and individual atomic motions of oxidized rubredoxin, a small 53 residue protein from thermophilic Pyrococcus furiosus (RdPf), by neutron scattering and computational simulations. The changes in motion have been explored in connection to their role in promoting reduction of the Fe+3 ion which is responsible for the electron transfer function of RdPf. Just above the dynamical transition temperature of 220 K which marks the onset of significant anharmonic motions of the protein, the computer simulations show both a significant reorientation of the average electrostatic force experienced by the Fe+3 ion and a dramatic rise in its strength. At higher temperatures, additional anharmonic modes become activated which dominate the electrostatic fluctuations experienced by the ion. At 360 K, close to the optimal growth temperature of Pyrococcus furiosus, computer simulations show that three anharmonic modes involving two conserved residues located at the protein active site (Ile7 and Ile40) give rise to the majority of the electrostatic fluctuations experienced by the Fe+3 ion and include displacements which allow solvent access to the ion. The low-frequency, high amplitude motions of these residues at low temperatures may be precursors of the high temperature, anharmonic motions necessary for protein function.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- DOE Office of Science; USDOE
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1021966
- Journal Information:
- Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry, Journal Name: Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry Journal Issue: 28 Vol. 115; ISSN 1520-6106
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
99 GENERAL AND MISCELLANEOUS
AMPLITUDES
COMPUTERIZED SIMULATION
ELECTRON TRANSFER
ELECTROSTATICS
FLUCTUATIONS
FUNCTIONS
GROWTH
IRON IONS
MOTION
NEUTRON DIFFRACTION
PROTEINS
REDUCTION
RESIDUES
RUBREDOXIN
SCATTERING
SOLVENTS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TRANSITION TEMPERATURE