Dr. Gary J. Pielak - Protein & protein complex stability in living cells

Gary J. Pielak

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

Protein & protein complex stability in living cells

The crowded and complex environment in cells is predicted to affect protein behavior compared to dilute buffer. My laboratory and our collaborators are examining crowding effects on the stability of proteins and their complexes in cells and under physiologically relevant crowded conditions using NMR. A challenge in these endeavors is detecting the test protein in a sea of crowders. NMR is ideally suited to overcome this challenge and provide high quality data on folded- and unfolded- proteins as well as free and bound forms of complexes. I will focus on equilibrium data acquired in living Escherichia coli cells, Xenopus laevis and Danio rerio oocytes as well as in vitro in concentrated cosolute solutions using 19F NMR. The cosolutes include synthetic polymers and their monomers, other proteins and lyophilized cytosol. The results show that crowding affects folding and binding in ways not always correctly predicted by simple theory. The differences point to opportunities for theoretical efforts and simulations.

Selected publications

• Speer, S. L., Stewart, C., Sapir, L., Harries, D., and Pielak, G. J. (2022) Macromolecular crowding is more than hard-core repulsions. Annual Review of Biophysics 51, in press
• Speer, S. L., Zheng, W., Jiang, X., Chu, I.-T., Guseman, A., Liu, M., Pielak, G., and Li, C. (2021) The intracellular environment affects protein-protein interactions. Proceedings of the National Academy of Sciences USA 118, e2019918118