Prediction of Active Residues of β-Galactosidase from Bacteroides Thetaiotaomicron

Abstract

© Springer International Publishing Switzerland 2014. Bacteroides thetaiotaomicron, a Gram-negative anaerobe and symbiotic commensal microbe, dominates the human intestinal tract; where it provides a range of beneficial metabolic tasks not encoded in the human genome. B. thetaiotaomicron uses various polysaccharides as its carbon and energy source, providing valuable monosaccharides for its host. Regarding dairy technology, the most important characteristic of B. thetaiotaomicron is its ability to degrade lactose.β-galactosidase from B. thetaiotaomicron belongs to thesubfamily GH-35. There is a lack of structural information about B. thetaiotaomicron β-galactosidase, including the active site and residues involved in lactose degradation. The aim of this research was to predict the residues of B. thetaiotaomicron β-galactosidase involved in substrate catalysis, to construct a model of its active site, and to predict residues involved in substrate binding.Amino acid sequences were retrieved from UNIPROT database. Sequence clustering and alignments were performed using UGENE 1.11.3.Docking studies were performed using Surflex-Dock. Our results indicate that proton donor and nucleophillic residues could be GLU182 and GLU123, respectively.These active residues of B. thetaiotaomicron β- galactosidase have not been reported previously.