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    Scientists Reveal Residue Specific Protein Folding and Unfolding Dynamics in Cells
    Update time: 2019-08-12
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    How proteins efficiently function in real biological environments with crowding and significant chemical and physical heterogeneity remains a fundamental question in biology. Typical cytoplasmic macromolecular concentrations are 300–450 g/L, which may affect protein folding and function. But how the cellular environment affects the protein folding process is unclear.

    Recently, the research team led by Prof. YAO Lishan from Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT), Chinese Academy of Sciences (CAS), has investigated the millisecond residue specific protein folding and unfolding dynamics in E. coli cells for two protein GB3 mutants using NMR. The results show that the protein folding and unfolding dynamics in cells is different from that in buffer (Fig. 1). Through a two-site exchange model, it is shown that the relative free energies of folded, unfolded and transition states are affected by the E.coli cellular environment (Fig. 2). Further investigation suggests that the change is likely due to the quinary interaction with crowded molecules in the cell.

    The work underlines the importance of cellular environment to protein folding kinetics and thermodynamics although this environmental effect may not be large enough to change the protein structure. Also this work emphasizes that one has to take the cellular environment into consideration to understand protein folding dynamics and thus functions in cells.

    This study, published in Journal of the American Chemical Society, was supported by National Key R&D Program of China, the National Natural Science Foundation of China, Shandong Provincial Natural Science Foundation, and the Taishan Scholars Program of Shandong Province.

    Figure 1. Conformational dynamics of MutX and MutY in E. coli cells (Image by SONG Xiangfei, CHEN Jingfei and YAO Lishan)

    Figure 2. Folding free energy (kJ/mol) landscapes of the two proteins in different environments (Image by SONG Xiangfei and YAO Lishan)

    (Text by SONG Xiangfei and YAO Lishan)


    CHENG Jing

    Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences

    Tel: 86-532-80662647

    E-mail: chengjing@qibebt.ac.cn


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