title: Function of trigger factor and DnaK in multidomain protein folding: increase in yield at the expense of folding speed.
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 beta-galactosidase (beta-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 beta-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.
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany.
authors.forename: Vishwas R
authors.initials: VR
authors.lastname: Agashe
authors.forename: Suranjana
authors.initials: S
authors.lastname: Guha
authors.forename: Hung-Chun
authors.initials: HC
authors.lastname: Chang
authors.forename: Pierre
authors.initials: P
authors.lastname: Genevaux
authors.forename: Manajit
authors.initials: M
authors.lastname: Hayer-Hartl
authors.forename: Markus
authors.initials: M
authors.lastname: Stemp
authors.forename: Costa
authors.initials: C
authors.lastname: Georgopoulos
authors.forename: F Ulrich
authors.initials: FU
authors.lastname: Hartl
authors.forename: José M
authors.initials: JM
authors.lastname: Barral
mesh_terms: D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism*; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D011387:Prokaryotic Cells / Q000201:enzymology*; D014176:Protein Biosynthesis / Q000502:physiology; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000502:physiology; D012270:Ribosomes / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D008156:Luciferases; D001616:beta-Galactosidase; C063842:dnaK protein, E coli; C403324:trigger factor, E coli; D019696:Peptidylprolyl Isomerase