cellulase and maltotetraose

Exploring new multifunctional enzymes and understanding the mechanisms of catalytic promiscuity will be of enormous industrial and academic values. In the present study, we reported the discovery and characterization of a multifunctional enzyme BSGH13 from Bacillus subtilis BS-5. Remarkably, BSGH13 possessed α-amylase, endoglucanase, and xylanase activities. To our knowledge, this was the first report on an amylase from Bacillus species having additional endoglucanase and xylanase activities. Subsequently, we analyzed the effects of aromatic residues substitution at each site of the active site architecture on ligand-binding affinity and catalytic specificity of BSGH13 by a combination of virtual mutation and site-directed mutagenesis approaches. Our results indicated that the introduction of aromatic amino acids Phe or Trp at the positions L182 and L183 altered the local interaction network of BSGH13 towards different substrates, thus changing the multifunctional properties of BSGH13. Moreover, we provided an expanded perspective on studies of multifunctional enzymes.

Topics: alpha-Amylases; Amino Acid Substitution; Bacillus subtilis; Bacterial Proteins; Catalytic Domain; Cellulase; Cellulose; Cloning, Molecular; Endo-1,4-beta Xylanases; Escherichia coli; Gene Expression; Genetic Vectors; Kinetics; Maltose; Models, Molecular; Mutation; Phenylalanine; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Recombinant Proteins; Structural Homology, Protein; Structure-Activity Relationship; Substrate Specificity; Tetroses; Tryptophan; Xylans