Global analysis of chaperone effects using a reconstituted cell-free translation system

Protein folding is often hampered by protein aggregation,which can be prevented by a variety of chaperones in the cell. A dataset that evaluates which chaperones are effective for aggregation-prone proteins would provide an invaluable resource not only for understanding the roles of chaperones, but also for broader applications in protein science and engineering. Therefore, we comprehensively evaluated the effects of the major Escherichia coli chaperones, trigger factor, DnaK/DnaJ/GrpE, and GroEL/GroES, on ∼800 aggregation-prone cytosolic E. coli proteins, using a reconstituted chaperone-free translation system. Statistical analyses revealed the robustness and the intriguing properties of chaperones. TheDnaK andGroEL systems drastically increased the solubilities of hundreds of proteins with weak biases, whereas trigger factor had only a marginal effect on solubility. The combined addition of the chaperoneswas effective for a subset of proteins that were not rescued by any single chaperone system, supporting the synergistic effect of these chaperones. The resource, which is accessible via a public database, can be used to investigate the properties of proteins of interest in terms of their solubilities and chaperone effects.