Structures of a glucose-tolerant β-glucosidase provide insights into its mechanism.

Cellulose can be converted to ethanol via the fermentation of glucose, which is considered as a promising green alternative for transportation fuels. The conversion of cellulose to glucose needs three enzymes, in which β-glucosidase (BGL) plays an essential role. However, BGL is inhibited by its own product glucose, greatly limiting its applications in industry.

Engineering of a thermostable esterase Est816 to improve its quorum-quenching activity and the underlying structural basis.

N-acyl-homoserine lactones (AHLs) are small diffusible molecules called autoinducers that mediate cell-to-cell communications. Enzymatic degradation of AHLs is a promising bio-control strategy known as quorum-quenching. To improve the quorum-quenching activity of a thermostable esterase Est816, which had been previously cloned, we have engineered the enzyme by random mutagenesis.

Efficient Secretion of the β-Galactosidase Bgal1-3 via both Tat-Dependent and Tat-Independent Pathways in Bacillus subtilis.

In this study, the twin-arginine (Tat) signal peptide PhoD was used to direct the secretion of the β-galactosidase Bgal1-3 into the growth medium of an engineered strain of Bacillus subtilis 168. After 24 h of cultivation, the extracellular activity reached 1.15 U/mL, representing 78% of the total activity.

Engineering a novel glucose-tolerant β-glucosidase as supplementation to enhance the hydrolysis of sugarcane bagasse at high glucose concentration.

Background: Most β-glucosidases reported are sensitive to the end product (glucose), making it the rate limiting component of cellulase for efficient degradation of cellulose through enzymatic route. Thus, there are ongoing interests in searching for glucose-tolerant β-glucosidases, which are still active at high glucose concentration. Although many β-glucosidases with different glucose-tolerance levels have been isolated and characterized in the past decades, the effects of glucose-tolerance on the hydrolysis of cellulose are not thoroughly studied.

Enhancing the Thermostability of Feruloyl Esterase EstF27 by Directed Evolution and the Underlying Structural Basis.

To improve the thermostability of EstF27, two rounds of random mutagenesis were performed. A thermostable mutant, M6, with six amino acid substitutions was obtained. The half-life of M6 at 55 °C is 1680 h, while that of EstF27 is 0.

Characterization of the cross-linked enzyme aggregates of a novel β-galactosidase, a potential catalyst for the synthesis of galacto-oligosaccharides.

A novel β-galactosidase (Bgal1-3) was isolated from a marine metagenomic library and then its cross-linked enzyme aggregates (CLEAs) were prepared. The enzymatic properties of Bgal1-3-CLEAs were studied and compared with that of the free enzyme. The thermostability and storage stability of Bgal1-3 were significantly improved after it was immobilized as CLEAs.

Identification and characterization of an unusual glycosyltransferase-like enzyme with β-galactosidase activity from a soil metagenomic library.

Glycosyltransferases and glycoside hydrolases are two diversified groups of carbohydrate-active enzymes (CAZymes) in existence, they serve to build and break down the glycosidic bonds, respectively, and both categories have formed many sequence-based families. In this study, a novel gene (glyt110) conferring β-galactosidase activity was obtained from a metagenomic library of Turpan Basin soil. Sequence analysis revealed that glyt110 encoded a protein of 369 amino acids that, rather than belonging to a family typically known for β-galactosidase activity, belonged to glycosyltransferase family 4.