Resumo

BAI, Xi et al. Efficient expression and characterization of a cold-active endo-1, 4-β-glucanase from Citrobacter farmeri by co-expression of Myxococcus xanthus protein S. Electron. J. Biotechnol. [online]. 2016, vol.19, n.6, pp.79-83. ISSN 0717-3458.  http://dx.doi.org/10.1016/j.ejbt.2016.10.005.

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.

Palavras-chave : Cellulose degradation; Cellulose; Cold-active enzyme; Endoglucanases; Enzymatic properties; Escherichia coli; Expression; Novel expression vector; N-terminal fusion; Protein S-tag; Recombinant protein.

        · texto em Inglês     · Inglês ( pdf )