Proteome analysis of a recombinant <it>Bacillus megaterium </it>strain during heterologous production of a glucosyltransferase

• Main Authors: Jahn Dieter, Malten Marco, Nimtz Manfred, Fürch Tobias, Hollmann Rajan, Wang Wei, Deckwer Wolf-Dieter
• Format: Article
• Language: English
• Published: BMC 2005-05-01
• Series: Proteome Science
• Online Access: http://www.proteomesci.com/content/3/1/4

<p>Abstract</p> <p>A recombinant <it>B. megaterium </it>strain was used for the heterologous production of a glucosyltransferase (dextransucrase). To better understand the physiological and metabolic responses of the host cell to cultivation and induction conditions, proteomic analysis was carried out by combined use of two-dimensional gel electrophoresis and mass spectrometry (2-DE/MS) for protein separation and identification.</p> <p>2-DE method was optimized for the separation of intracellular proteins. Since the genome of <it>B. megaterium </it>is not yet available, peptide sequencing using peptide fragment information obtained from nanoelectrospray ionization quadrupole-time-of-flight tandem mass spectrometry (ESI-QqTOF MS/MS) was applied for protein identification. 167 protein spots were identified as 149 individual proteins, including most enzymes involved in the central carbon metabolic pathways and many enzymes related to amino acid synthesis and protein synthesis. Based on the results a 2-DE reference map and a corresponding protein database were constructed for further proteomic approaches on <it>B. megaterium</it>.</p> <p>For the first time it became possible to perform comparative proteomic analysis on <it>B. megaterium </it>in a batch culture grown on glucose with xylose induction for dextrasucrase production. No significant differences were observed in the expression changes of enzymes of the glycolysis and TCA cycle, indicating that dextransucrase production, which amounted to only 2 % of the entire protein production, did not impose notable metabolic or energetic burdens on the central carbon metabolic pathway of the cells. However, a short-term up-regulation of aspartate aminotransferase, an enzyme closely related to dextransucrase production, in the induced culture demonstrated the feasibility to use 2-DE method for monitoring dextransucrase production. It was also observed that under the cultivation conditions used in this study <it>B. megaterium </it>tended to channel acetyl-CoA into pathways of polyhydroxybutyrate production. No expression increases were found with cytosolic chaperones such as GroEL and DnaK during dextransucrase production and secretion, whereas a strong up-regulation of the oligopeptide-binding protein OppA was observed in correlation with an increased secretion of dextransucrase into the culture medium.</p>