Solubility enhancement of aggregation-prone heterologous proteins by fusion expression using stress-responsive Escherichia coli protein, RpoS

Jin Seung Park, Kyung Yeon Han, Jong Ho Lee, Jong Am Song, Keum Young Ahn, Hyuk Seong Seo, Sang Jun Sim, Seung Wook Kim, Jeewon Lee

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26 Citations (Scopus)


Background: The most efficient method for enhancing solubility of recombinant proteins appears to use the fusion expression partners. Although commercial fusion partners including maltose binding protein and glutathione-S-transferase have shown good performance in enhancing the solubility, they cannot be used for the proprietory production of commercially value-added proteins and likely cannot serve as universal helpers to solve all protein solubility and folding issues. Thus, novel fusion partners will continue to be developed through systematic investigations including proteome mining presented in this study. Results: We analyzed the Escherichia coli proteome response to the exogenous stress of guanidine hydrochloride using 2-dimensional gel electrophoresis and found that RpoS (RNA polymerase sigma factor) was significantly stress responsive. While under the stress condition the total number of soluble proteins decreased by about 7 %, but a 6-fold increase in the level of RpoS was observed, indicating that RpoS is a stress-induced protein. As an N-terminus fusion expression partner, RpoS increased significantly the solubility of many aggregation-prone heterologous proteins in E. coli cytoplasm, indicating that RpoS is a very effective solubility enhancer for the synthesis of many recombinant proteins. RpoS was also well suited for the production of a biologically active fusion mutant of Pseudomonas putida cutinase. Conclusion: RpoS is highly effective as a strong solubility enhancer for aggregation-prone heterologous proteins when it is used as a fusion expression partner in an E. coli expression system. The results of these findings may, therefore, be useful in the production of other biologically active industrial enzymes, as successfully demonstrated by cutinase.

Original languageEnglish
Article number15
JournalBMC Biotechnology
Publication statusPublished - 2008 Feb 19

Bibliographical note

Funding Information:
We thank Professor Hang Chul Shin at Soongsil University for kindly providing the gene clones of mpINS and G-CSF. We also appreciate Professors Won Tae Lee and Hyun Soo Cho at Yonsei University for the kind donation of ppGRN, AID, and NACHT clones, respectively. This study was supported by the National Research Laboratory Project of the Ministry of Science and Technology (grant no. ROA-2007-000-20084-0) of the Republic of Korea. This work was also supported by the Korea Health 21 R&D Project of the Ministry of Health & Welfare (grant no. A050750), by grant 031-061-029 of the Ecotechnopia 21 project of the Ministry of Environment, and by the Second Brain Korea 21 Project. Further supports from the Korea Science and Engineering Foundation (grant no. R01-2005-000-10355-0) and the Korea Research Foundation (grant no. KRF-2004-041-D00180) are also appreciated.

ASJC Scopus subject areas

  • Biotechnology


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