NSF-BSF: Macromolecular crowding in vitro and in cells

Protein-protein interactions regulate all cellular functions, yet they are almost always studied in water rather than in the complex and crowded environment that exists inside cells. The results of this project will fill a key gap that prevents a complete description of metabolism. The goal of moving quantitative biophysics from simple solutions to crowded environments, including inside living cells, is a major challenge with important outcomes. The knowledge gained will add to both the fundamental understanding of biology and inform efforts to produce and stabilize protein-based reagents. The work will also facilitate the training of undergraduate and graduate students in the practice of cutting-edge research. All these efforts are key to building the US bioeconomy.The goal of the project is to gain broadly-applicable knowledge about protein- and protein complex- stability under crowded conditions. A new model combining hard and soft interactions claiming to explain macromolecular crowding effects on the free energy, enthalpy and entropy of protein- and protein complex- stability will be tested on three protein systems using two types or crowding molecules. One system is used to assesses protein stability. The other two systems assess simple dimerization and dimerization with folding. The two types of crowding molecules are industrially important synthetic polymers and a series of de novo designed proteins. This project will use detection system of 19F nuclear magnetic resonance spectroscopy and isothermal titration calorimetry. This collaborative US/Israel project is supported by the US National Science Foundation and the Israeli Binational Science Foundation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.