Enhanced Enzyme Stability through Fusion of Self-Assembled Cellulose Binding Domain

Enzyme stability has been a significant concern for protein engineers due to its industrial importance in biocatalytic processes. Here, we present the enhanced enzyme stability by fusing the enzyme to a nano-particle-like cellulose binding domain (CBD) expressed in engineered Escherichia coli. The CBD from Cellulomonas fimi fused with a β-glucuronidase (GusA) derived from E. coli was expressed, purified, and characterized. Whereas the fusion construct retained enzymatic activity, significant differences in thermostability and pH stability were observed. In particular, the CBD-GusA variant showed almost 2-fold increased half-lives compared to findings for the free GusA enzyme. In addition, the CBD-GusA protein exhibited increased methanol tolerance and decreased protease accessibility compared to those of the free GusA. The fusion strategy presented here reveals a surprising means for the stabilization of enzymes and stresses the importance for improving stability of enzymes used in industrial applications.