期刊
出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.2019918118
关键词
macromolecular crowding; protein; protein-protein interactions; thermodynamics
资金
- NSF [MCB-1410854, CHE-1726291]
- NIH [R01GM127291, T32 GM008570, F31 GM126763]
- Ministry of Science and Technology of China [2017YFA0505400, 2018YFE0202300]
- National Natural Science Foundation of China [21925406, 21921004, 21991080]
- National Cancer Institute [P30 CA016086]
Protein-protein interactions are more influenced by chemical interactions than hard-core repulsions in cells; increasing negative charge on the homodimer surface enhances stability in cells; oocytes are less crowded than E. coli cells, leading to greater stability of protein complexes.
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 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.
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