Next Article Table of Contents

Accelerated Publication

Protein Dynamics in Living Cells^†

Julie E. Bryant,^‡ Juliette T. J. Lecomte,^§ Andrew L. Lee,^@ Gregory B. Young, and Gary J. Pielak*^‡^@

Departments of Chemistry and of Biochemistry and Biophysics, Division of Medicinal Chemistry and Natural Products, and Lineberger Cancer Research Center, University of North Carolina, Chapel Hill, North Carolina 27599, and Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802

Biochemistry, 2005, 44 (26), pp 9275–9279

DOI: 10.1021/bi050786j

Publication Date (Web): June 10, 2005

†

This work was supported by the NSF (Grant MCB 0212939 to G.J.P.) and the NIH (Grant GM-54217 to J.T.J.L.). J.E.B. was partially supported by a Dobbins Fellowship.

‡

Department of Chemistry, University of North Carolina.

The Pennsylvania State University.

Division of Medicinal Chemistry and Natural Products, University of North Carolina.

Department of Biochemistry and Biophysics, University of North Carolina.

Lineberger Cancer Research Center, University of North Carolina.

To whom correspondence should be addressed: Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599. Phone: (919) 966-3671. Fax: (919) 966-3675. E-mail: gary_pielak@unc.edu.

Abstract

A protein's structure is most often used to explain its function, but function also depends on dynamics. To date, protein dynamics have been studied only in vitro under dilute solution conditions where solute concentrations are typically less than 10 g/L, yet proteins function in a crowded environment where the solute concentration can exceed 400 g/L. Does the intracellular environment affect protein dynamics? The answer will help in assessing the biological significance of the NMR-derived dynamics data collected to date. We investigated fast protein dynamics inside living Escherichia coli by using in-cell NMR. The backbone dynamics of apocytochrome b₅ were quantified using {¹H}−¹⁵N nuclear Overhauser effect (nOe) measurements, which characterize motions on the pico- to nanosecond time scale. The overall trend of backbone dynamics remains the same in cells. Some of the nOe values differ, but most of the differences track the increased intracellular viscosity rather than a change in dynamics. Therefore, it appears that dilute solution steady-state {¹H}−¹⁵N nOe measurements provide biologically relevant information about pico- to nanosecond backbone motion in proteins.

View: Full Text HTML | Hi-Res PDF