Ionic strength-dependent conformations of a ubiquitin-like small archaeal modifier protein (SAMP1) from Haloferax volcanii

Authors

  • Kaiqin Ye,

    1. Hefei National Laboratory for Physical Sciences at Microscale, School of Life Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
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  • Shanhui Liao,

    1. Hefei National Laboratory for Physical Sciences at Microscale, School of Life Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
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  • Wen Zhang,

    1. Hefei National Laboratory for Physical Sciences at Microscale, School of Life Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
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  • Kai Fan,

    1. Hefei National Laboratory for Physical Sciences at Microscale, School of Life Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
    2. Reproductive Medical Center, Nanjing General Hospital of Nanjing Military Command, Nanjing, People's Republic of China
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  • Xuecheng Zhang,

    1. School of Life Sciences, Anhui University, Hefei, Anhui, People's Republic of China
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  • Jiahai Zhang,

    1. Hefei National Laboratory for Physical Sciences at Microscale, School of Life Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
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  • Chao Xu,

    1. Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
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  • Xiaoming Tu

    Corresponding author
    1. Hefei National Laboratory for Physical Sciences at Microscale, School of Life Science, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
    • Correspondence to: Xiaoming Tu, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China. E-mail: xmtu@ustc.edu.cn.

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Abstract

Eukaryotic ubiquitin and ubiquitin-like systems play crucial roles in various cellular biological processes. In this work, we determined the solution structure of SAMP1 from Haloferax volcanii by NMR spectroscopy. Under low ionic conditions, SAMP1 presented two distinct conformations, one folded β-grasp and the other disordered. Interestingly, SAMP1 underwent a conformational conversion from disorder to order with ion concentration increasing, indicating that the ordered conformation is the functional form of SAMP1 under the physiological condition of H. volcanii. Furthermore, SAMP1 could interact with proteasome-activating nucleotidase B, supposing a potential role of SAMP1 in the protein degradation pathway mediated by proteasome.

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