Structural-Functional Analysis of Biopolymers and Their Complexes

Molecular Biology

, Volume 43, Issue 3, pp 410-417

Synthesis in Escherichia coli cells and characterization of the active exoribonuclease of severe acute respiratory syndrome coronavirus

  • P. ChenAffiliated withState Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan UniversityDepartment of Pathophysiology, Basic Medical College of Zhengzhou University
  • , T. HuAffiliated withState Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University
  • , M. JiangAffiliated withState Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University
  • , D. GuoAffiliated withState Key Laboratory of Virology and Modern Virology Research Centre, College of Life Sciences, Wuhan University Email author 

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Abstract

The nsp14 protein, an exoribonuclease of the DEDD superfamily encoded by severe acute respiratory syndrome coronavirus (SARS-CoV), was expressed in fusion with different affinity tags. The recombinant nsp14 proteins with either GST fusion or 6-histidine tag were shown to possess ribonuclease activity but nsp14 with a short MGHHHHHHGS tag sequence at the N-terminus increased the solubility of nsp14 protein and facilitated the protein purification. Mutations of the conserved residues of nsp14 resulted in significant attenuation but not abolishment of the ribonuclease activity. Combination of fluorescence and circular dichroism spectroscopy analyses showed that the conformational stability of nsp14 protein varied with many external factors such as pH, temperature and presence of denaturing chemicals. These results provide new information on the structural features and would be helpful for further characterization of this functionally important protein.

Key words

SARS coronavirus exoribonuclease affinity tag mutagenesis conformational stability