title: Modulation of the tendency towards inclusion body formation of recombinant protein by the addition of glucose in the araBAD promoter system of Escherichia coli.
abstract: We attempted to modulate the overall protein expression rate through the addition of a repressor against the araBAD promoter system of Escherichia coli, in which glucose was used as a repressor. Therefore, 0.5% L-arabinose was initially contained as an inducer in culture medium, and either 2% glucose or 2% glycerol was used as a carbon source, and it was found that the expression of recombinant interferon-alpha could be observed at the beginning of the batch culture when glycerol was used as a carbon source. However, when glucose was used, the initiation of recombinant interferon-alpha expression was delayed compared with that when glycerol was used. Furthermore, when the addition of 0.5% glucose was carried out once or twice after 0.5% L-arabinose induction during DO-stat fed-batch culture, the distributions of soluble and insoluble recombinant interferon-alpha were modulated. When glucose was not added after the induction of L-arabinose, all of the expressed recombinant interferon-alpha formed an inclusion body during the later half of culturing. However, when glucose was added after induction, the expressed recombinant interferon-alpha, did not all form an inclusion body, and about half of the total recombinant interferon-alpha was expressed in a soluble form. It was deduced that the addition of glucose after the induction of L-arabinose might lower the cAMP level, and thus, CAP (catabolite activator protein) might not be activated. The transcription rate of recombinant interferon-alpha in the araBAD promoter system might be delayed by the partial repression. This inhibition of the transcription rate probably resulted in more soluble interferon-alpha expression caused by the reduction of the protein synthesis rate.
authors: Division of Food and Biotechnology, Chungju National University, Chungju 380-702, Korea.
authors: You-Jin
authors: YJ
authors: Lee
authors: Kyung-Hwan
authors: KH
authors: Jung
mesh_terms: D004926:Escherichia coli / Q000235:genetics*; D005947:Glucose / Q000494:pharmacology*; D002479:Inclusion Bodies / Q000378:metabolism*; D007370:Interferon Type I / Q000096:biosynthesis*; D016898:Interferon-alpha / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins
chemical_list: D007370:Interferon Type I; D016898:Interferon-alpha; D011994:Recombinant Proteins; D005947:Glucose