Efficient expression and characterization of a cold-active endo-1, 4-β-glucanase from Citrobacter farmeri by co-expression of Myxococcus xanthus protein S

• Xi Bai ^[1] ; Xianjun Yuan ^[1] ; Aiyou Wen ^[3] ; Junfeng Li ^[1] ; Yunfeng Bai ^[2] ; Tao Shao ^[1]
  1. [1] Nanjing Agricultural University

     Nanjing Agricultural University

     China

     
  2. [2] Jiangsu Academy of Agricultural Sciences

     Jiangsu Academy of Agricultural Sciences

     China

     
  3. [3] University of Science and Technology of Anhui College of Animal Science

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• Localización: Electronic Journal of Biotechnology, ISSN-e 0717-3458, Vol. 19, Nº. 6, 2016, págs. 79-83
• Idioma: inglés
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  • Background: Cold-active endo-1, 4-β-glucanase (EglC) can decrease energy costs and prevent product denaturation in biotechnological processes. However, the nature EglC from C. farmeri A1 showed very low activity (800 U/L). In an attempt to increase its expression level, C. farmeri EglC was expressed in Escherichia coli as an N-terminal fusion to protein S (ProS) from Myxococcus xanthus. Results: A novel expression vector, pET(ProS-EglC), was successfully constructed for the expression of C. farmeri EglC in E. coli. SDS-PAGE showed that the recombinant protein (ProS-EglC) was approximately 60 kDa. The activity of ProS-EglC was 12,400 U/L, which was considerably higher than that of the nature EglC (800 U/L). ProS-EglC was active at pH 6.5-pH 8.0, with optimum activity at pH 7.0. The recombinant protein was stable at pH 3.5-pH 6.5 for 30 min. The optimal temperature for activity of ProS-EglC was 30°C-40°C. It showed greater than 50% of maximum activity even at 5°C, indicating that the ProS-EglC is a cold-active enzyme. Its activity was increased by Co2+ and Fe2+, but decreased by Cd2+, Zn2+, Li+, methanol, Triton-X-100, acetonitrile, Tween 80, and SDS. Conclusions: The ProS-EglC is promising in application of various biotechnological processes because of its cold-active characterizations. This study also suggests a useful strategy for the expression of foreign proteins in E. coli using a ProS tag.