Suppressing glucose uptake and acetic acid production increases membrane protein overexpression in Escherichia coli

Microbial Cell Factories

Research

Marina Ignatushchenko¹  Emma Bäcklund²  Gen Larsson² 

[1] Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE 171 77, Stockholm, Sweden;Div of Bioprocess Technology, School of Biotechnology, Albanova University Center, Royal Institute of Technology, SE 106 91, Stockholm, Sweden;

关键词: Minimal Salt Medium;    Acetic Acid Production;    OD600 Unit;    Substrate Uptake Rate;    Acetic Acid Formation;   

DOI  :  10.1186/1475-2859-10-35

 received in 2010-10-20, accepted in 2011-05-17,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundThe production of integral membrane spanning proteins (IMP's) constitutes a bottleneck in pharmaceutical development. It was long considered that the state-of-the-art was to produce the proteins as inclusion bodies using a powerful induction system. However, the quality of the protein was compromised and the production of a soluble protein that is incorporated into the membrane from which it is extracted is now considered to be a better method. Earlier research has indicated that a slower rate of protein synthesis might overcome the tendency to form inclusion bodies. We here suggest the use of a set of E. coli mutants characterized by a slower rate of growth and protein synthesis as a tool for increasing the amount of soluble protein in high- throughput protein production processes.ResultsA set of five IMP's was chosen which were expressed in three mutants and the corresponding WT cell (control). The mutations led to three different substrate uptake rates, two of which were considerably slower than that of the wild type. Using the mutants, we were able to express three out of the five membrane proteins. Most successful was the mutant growing at 50% of the wild type growth rate. A further effect of a low growth rate is a low acetic acid formation, and we believe that this is a possible reason for the better production. This hypothesis was further supported by expression from the BL21(DE3) strain, using the same plasmid. This strain grows at a high growth rate but nevertheless yields only small amounts of acetic acid. This strain was also able to express three out of the five IMP's, although at lower quantities.ConclusionsThe use of mutants that reduce the specific substrate uptake rate seems to be a versatile tool for overcoming some of the difficulties in the production of integral membrane spanning proteins. A set of strains with mutations in the glucose uptake system and with a lower acetic acid formation were able to produce three out of five membrane proteins that it was not possible to produce with the corresponding wild type.

【 授权许可】

Unknown   
© Bäcklund et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.