N-terminal domains of native multidomain proteins have the potential to assist de novo folding of their downstream domains in vivo by acting as solubility enhancers

Authors

  • Chul Woo Kim,

    1. Department of Biotechnology, College of Engineering, Yonsei University, Seodaemun-Gu, Seoul 120-749, Korea
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  • Kyoung Sim Han,

    1. Protheon Incorporated, Yonsei Engineering Research Center B120E, Seodaemun-Gu, Seoul 120-749, Korea
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  • Ki-Sun Ryu,

    1. Department of Biotechnology, College of Engineering, Yonsei University, Seodaemun-Gu, Seoul 120-749, Korea
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  • Byung Hee Kim,

    1. Department of Biotechnology, College of Engineering, Yonsei University, Seodaemun-Gu, Seoul 120-749, Korea
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  • Kyun-Hwan Kim,

    1. Department of Pharmacology, School of Medicine, Konkuk University, 380-701, Korea
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  • Seong Il Choi,

    Corresponding author
    1. Department of Biotechnology, College of Engineering, Yonsei University, Seodaemun-Gu, Seoul 120-749, Korea
    2. Institute of Life Science and Biotechnology, Yonsei University, Seodaemun-Gu, Seoul 120-749, Korea
    • Institute of Life Science and Biotechnology, Yonsei University, 134 Shinchon-Dong, Seodaemun-Gu, Seoul 120-749, Korea; fax: 82-2-392-3582.
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  • Baik L. Seong

    1. Department of Biotechnology, College of Engineering, Yonsei University, Seodaemun-Gu, Seoul 120-749, Korea
    2. Protheon Incorporated, Yonsei Engineering Research Center B120E, Seodaemun-Gu, Seoul 120-749, Korea
    3. Institute of Life Science and Biotechnology, Yonsei University, Seodaemun-Gu, Seoul 120-749, Korea
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Abstract

The fusion of soluble partner to the N terminus of aggregation-prone polypeptide has been popularly used to overcome the formation of inclusion bodies in the E. coli cytosol.

The chaperone-like functions of the upstream fusion partner in the artificial multidomain proteins could occur in de novo folding of native multidomain proteins. Here, we show that the N-terminal domains of three E. coli multidomain proteins such as lysyl-tRNA synthetase, threonyl-tRNA synthetase, and aconitase are potent solubility enhancers for various C-terminal heterologous proteins. The results suggest that the N-terminal domains could act as solubility enhancers for the folding of their authentic C-terminal domains in vivo. Tandem repeat of N-terminal domain or insertion of aspartic residues at the C terminus of the N-terminal domain also increased the solubility of fusion proteins, suggesting that the solubilizing ability correlates with the size and charge of N-terminal domains. The solubilizing ability of N-terminal domains would contribute to the autonomous folding of multidomain proteins in vivo, and based on these results, we propose a model of how N-terminal domains solubilize their downstream domains.

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