The intracellular environment affects protein–protein interactions

Shannon L. Speer, Wenwen Zheng, Xin Jiang, I-Te Chu, Alex J. Guseman, Maili Liu, Gary J. Pielak, Conggang Li
2021 Proceedings of the National Academy of Sciences of the United States of America  
Protein–protein interactions are essential for life but rarely thermodynamically quantified in living cells. In vitro efforts show that protein complex stability is modulated by high concentrations of cosolutes, including synthetic polymers, proteins, and cell lysates via a combination of hard-core repulsions and chemical interactions. We quantified the stability of a model protein complex, the A34F GB1 homodimer, in buffer, Escherichia coli cells and Xenopus laevis oocytes. The complex is more
more » ... stable in cells than in buffer and more stable in oocytes than E. coli. Studies of several variants show that increasing the negative charge on the homodimer surface increases stability in cells. These data, taken together with the fact that oocytes are less crowded than E. coli cells, lead to the conclusion that chemical interactions are more important than hard-core repulsions under physiological conditions, a conclusion also gleaned from studies of protein stability in cells. Our studies have implications for understanding how promiscuous—and specific—interactions coherently evolve for a protein to properly function in the crowded cellular environment.
doi:10.1073/pnas.2019918118 pmid:33836588 fatcat:g5aepg66tjawbcflom3qq6njcu