Function of trigger factor and DnaK in multidomain protein folding: increase in yield at the expense of folding speed.
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.
Agashe
Vishwas R
VR
Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany.
Guha
Suranjana
S
Chang
Hung-Chun
HC
Genevaux
Pierre
P
Hayer-Hartl
Manajit
M
Stemp
Markus
M
Georgopoulos
Costa
C
Hartl
F Ulrich
FU
Barral
José M
JM
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
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