Direct Measurement of Protein Dynamics In Vivo
Labeling strategy for probing live cells using quasi-elastic neutron scattering (QENS). Graph: QENS spectra of uninduced cells (blue) and cells with expressed GroEL protein (red) in the deuterium oxide (D2O) bu?er. [Reprinted with permission from Anunciado, D. B., et al. “In Vivo Protein Dynamics on the Nanometer Length Scale and Nanosecond Time Scale.” J. Phys. Chem. Lett. 8(8), 1899–1904 (2017). DOI: 10.1021/acs.jpclett.7b00399. Copyright 2017 American Chemical Society.]
Quasi-elastic neutron scattering was used to study the protein GroEL in vivo. Protiated GroEL was over-expressed in deuterated Escherichia coli cells by addition of protiated amino acids during induction of GroEL. The data showed retardation factors of ~2 and ~4 for the internal dynamics and global diffusion of the protein, compared to those of the protein in solution at the same concentration. Comparison with literature values suggests that the effective diffusivity of proteins depends on the length or time scale probed. Selective isotope labeling of biomolecules in cells opens up new lines of biological research using “in-cell neutron scattering” to extract information on dynamics of biomolecular systems that is unobtainable by other analysis techniques.
Instruments and Facilities
Quasi-elastic neutron scattering, BASIS neutron backscattering spectrometer at Spallation Neutron Source at Oak Ridge National Laboratory.
Qiu Zhang: technical assistance. Manuscript authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy (DOE Neutron scattering experiments at Oak Ridge National Laboratory’s (ORNL) Spallation Neutron Source (SNS) support: Office of Basic Energy Sciences (OBES) Scientific User Facilities Division, DOE Office of Science. Additional funding: Adaptive Biosystems Imaging project (ERKP851) and Center for Structural Molecular Biology (Project ERKP291) supported by DOE Office of Biological and Environmental Research (OBER).
Anunciado, D. B., et al. “In Vivo Protein Dynamics on the Nanometer Length Scale and Nanosecond Time Scale.” J. Phys. Chem. Lett. 8(8), 1899–1904 (2017). [DOI:10.1021/acs.jpclett.7b00399]