Effect of the cellulose-binding domain on the catalytic activity of a β-glucosidase from Saccharomycopsis fibuligera

Sarath B. Gundllapalli, Isak S. Pretorius, Ricardo R. Cordero Otero*

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Enzyme engineering was performed to link the β-glucosidase enzyme (BGL1) from Saccharomycopsis fibuligera to the cellulose-binding domain (CBD2) of Trichoderma reesei cellobiohydrolase (CBHII) to investigate the effect of a fungal CBD on the enzymatic characteristics of this non-cellulolytic yeast enzyme. Recombinant enzymes were constructed with single and double copies of CBD2 fused at the N-terminus of BGL1 to mimic the two-domain organization displayed by cellulolytic enzymes in nature. The engineered S. fibuligera β-glucosidases were expressed in Saccharomyces cerevisiae under the control of phosphoglycerate-kinase-1 promoter (PGK1 P ) and terminator (PGK1 T ) and yeast mating pheromone α-factor secretion signal (MFα1 S ). The secreted enzymes were purified and characterized using a range of cellulosic and non-cellulosic substrates to illustrate the effect of the CBD on their enzymatic activity. The results indicated that the recombinant enzymes of BGL1 displayed a 2-4-fold increase in their hydrolytic activity toward cellulosic substrates like avicel, amorphous cellulose, bacterial microcrystalline cellulose, and carboxy methyl cellulose in comparison with the native enzyme. The organization of the CBD in these recombinant enzymes also resulted in enhanced substrate affinity, molecular flexibility and synergistic activity, thereby improving the ability of the enzymes to act on and hydrolyze cellulosic substrates, as characterized by adsorption, kinetics, thermal stability, and scanning electron microscopic analyses.

Original languageEnglish
Pages (from-to)413-421
Number of pages9
JournalJournal of Industrial Microbiology and Biotechnology
Volume34
Issue number6
DOIs
Publication statusPublished - Jun 2007
Externally publishedYes

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