Hybrid bacillus endo-(1–3, 1–4)-β-glucanases: Construction of recombinant genes and molecular properties of the gene products

• DOI: 10.1007/bf02907584
• Publication Date: 2008-05-17T03:57:53Z
• Authors: Rainer Borriss; Ole Olsen; Karl Kristian Tho...; Diter Von Wettstein
• Keywords: 0301 basic medicine; Base Sequence; Glycoside Hydrolases; Genetic Vectors; Molecular Sequence Data; Bacillus; Recombinant Proteins; Kinetics; 03 medical and health sciences; Genes; Genes, Bacterial; Two-Hybrid System Techniques; Escherichia coli; Amino Acid Sequence; Cloning, Molecular; Plasmids

Hybrid beta-glucanase genes were constructed by the reciprocal exchange of the two halves of the isolated beta-glucanase genes from Bacillus amyloliquefaciens and B. macerans. The beta-glucanase hybrid enzyme 1 (H1) contains the 107 amino-terminal residues of mature B. amyloliquefaciens beta-glucanase and the 107 carboxyl-terminal amino acid residues of B. macerans beta-glucanase. The reciprocal beta-glucanase hybrid enzyme 2 (H2) consists of the 105 amino-terminal residues from the B. macerans enzyme and the carboxyl-terminal 107 amino acids from B. amyloliquefaciens. The biochemical properties of the two hybrid enzymes differ significantly from each other as well as from both parental beta-glucanases. Hybrid beta-glucanase H1 exhibits increased thermostability in comparison to other beta-glucanases, especially in an acidic environment. This hybrid enzyme has maximum activity between pH 5.6 and 6.6, whereas the pH-optimum for enzymatic activity of B. amyloliquefaciens beta-glucanase was found to be at pH 6 to 7 and for B. macerans at pH 6.0 to 7.5. Hybrid enzyme 1 being more heat stable than both parental enzymes represents a case of intragenic heterosis. Hybrid beta-glucanase 2 (H2) was found to be more thermolabile than the naturally occurring beta-glucanases it was derived from and the pH-optimum for enzymatic activity was determined to be between pH 7 and pH 8.