title: Divergent effects of chaperone overexpression and ethanol supplementation on inclusion body formation in recombinant Escherichia coli.
abstract: The proper folding of aggregation-prone recombinant proteins in Escherichia coli can be facilitated by co-overexpressing specific molecular chaperones or by culturing the cells in the presence of ethanol or other agents that upregulate the synthesis of all heat-shock proteins (hsps). We have investigated the effect of combining direct chaperone overproduction with ethanol supplementation on the cytoplasmic folding of two aggregation-prone model proteins, preS2-S'-beta-galactosidase and human SPARC. In 25-ml shake flask cultures grown at 30 degrees C, addition of 3% (v/v) ethanol to the growth medium prior to inoculation improved the chaperone-mediated increase in the yields of active preS2-S'-beta-galactosidase 1.5- to 2-fold. When cultures overexpressing the dnaKJ operon were grown in the presence of ethanol, the levels of enzymatic activity were 5-fold higher relative to control cells and preS2-S'-beta-galactosidase aggregation was almost entirely abolished. Combining DnaK-DnaJ overexpression and growth of the cells at temperatures lower than 30 degrees C did not result in a comparable increase in activity. Although the individual effects of ethanol supplementation and dnaKJ overproduction were more limited when the culture volume was raised, a synergistic improvement in preS2-S'-beta-galactosidase activity was observed when the two approaches were used in concert. In contrast, ethanol supplementation promoted the aggregation of human SPARC, a protein exhibiting a chaperone dependency similar to that of preS2-S'-beta-galactosidase. Our results show that ethanol can exert complex and divergent effects on inclusion body formation and that the beneficial effect of the solvent on recombinant protein folding cannot simply be explained by an increase in the intracellular concentration of molecular chaperones.
authors.affiliation: Department of Chemical Engineering, University of Washington, Seattle 98195, USA.
authors.forename: J G
authors.initials: JG
authors.lastname: Thomas
authors.forename: F
authors.initials: F
authors.lastname: Baneyx
mesh_terms: D003001:Cloning, Molecular / Q000379:methods; D004792:Enzyme Precursors / Q000096:biosynthesis; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D000431:Ethanol / Q000494:pharmacology*; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D006358:Hot Temperature; D006801:Humans; D018832:Molecular Chaperones / Q000096:biosynthesis*; D017510:Protein Folding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D001616:beta-Galactosidase / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D004792:Enzyme Precursors; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D000431:Ethanol; D001616:beta-Galactosidase