Cell
Volume 117, Issue 2, 16 April 2004, Pages 199-209
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Article
Function of Trigger Factor and DnaK in Multidomain Protein Folding: Increase in Yield at the Expense of Folding Speed

https://doi.org/10.1016/S0092-8674(04)00299-5Get rights and content
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Abstract

Trigger factor and DnaK protect nascent protein chains from misfolding and aggregation in the E. coli cytosol, but how these chaperones affect the mechanism of de novo protein folding is not yet understood. Upon expression under chaperone-depleted conditions, multidomain proteins such as bacterial β-galactosidase (β-gal) and eukaryotic luciferase fold by a rapid but inefficient default pathway, tightly coupled to translation. Trigger factor and DnaK improve the folding yield of these proteins but markedly delay the folding process both in vivo and in vitro. This effect requires the dynamic recruitment of additional trigger factor molecules to translating ribosomes. While β-galactosidase uses this chaperone mechanism effectively, luciferase folding in E. coli remains inefficient. The efficient cotranslational domain folding of luciferase observed in the eukaryotic system is not compatible with the bacterial chaperone system. These findings suggest important differences in the coupling of translation and folding between bacterial and eukaryotic cells.

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These authors contributed equally to this work.