title: Enhanced cell-free protein synthesis using a S30 extract from Escherichia coli grown rapidly at 42 degrees C in an amino acid enriched medium.
abstract: Growths of Escherichia coli strain A19 were investigated in a 5-L fermentor at 37 and 42 degrees C either in Pratt's medium (a standard medium for cell-free protein synthesis using its S30 extract) or in a casamino acids supplemented Pratt's medium (aa-enriched medium). Specific growth rates in Pratt's medium at 37 and 42 degrees C were 0.77 and 0.46 h(-1), respectively, whereas those in the aa-enriched medium at 37 and 42 degrees C were 0.87 and 1.49 h(-1), respectively. The extent of cell-free chloramphenicol acetyltransferase (CAT) synthesis was compared at 37 degrees C incubation (from a plasmid pK7-CAT) for S30 extracts prepared from the cells cultured in the aa-enriched medium at 37 or 42 degrees C. A 40% increase in CAT synthesis occurred when the 42 degrees C/S30 extract was used as compared with 37 degrees C/S30 extract. CAT and both the light and heavy chains (Lc and Hc) of the Fab fragment of an antibody 6D9 were synthesized at 37 degrees C in the cell-free synthesis in the presence of [(14)C]Leu. Their reaction mixtures were subjected to SDS-PAGE autoradiographic analysis. It was found that most of the synthesized proteins were in the soluble fraction when 42 degrees C/S30 extract was used, suggesting that the 42 degrees C/S30 extract contained greater amounts of various protein folding factors. A dialysis membrane minibioreactor with a reaction volume ca. 0.5 mL was handmade by the authors. The advantages of the minibioreactor are a simple configuration, a low manufacturing cost, and the capability of the dialysis membrane replacement. Increased CAT synthesis was also observed for continuous exchange cell-free (CECF) protein synthesis at 37 degrees C when the 42 degrees C/S30 extract was used in the minibioreactor. Some plausible reasons to give higher protein synthesis activity of the 42 degrees C/S30 extract are discussed.
authors.affiliation: Laboratory of Molecular Biotechnology, Graduate School of Bio- and Agro-Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan. yamanetu@agr.nagoya-u.ac.jp
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Yamane
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Takehiro
authors.initials: T
authors.lastname: Nagasaka
authors.forename: Hideo
authors.initials: H
authors.lastname: Nakano
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D001345:Autoradiography; D019149:Bioreactors; D002474:Cell-Free System; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D005285:Fermentation; D006358:Hot Temperature; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D000596:Amino Acids; D003470:Culture Media; D011994:Recombinant Proteins; D015500:Chloramphenicol O-Acetyltransferase