Intra- and Extracellular β-Galactosidases from Bifidobacterium bifidum and B. infantis : Molecular Cloning, Heterologous Expression, and Comparative Characterization

• DOI: 10.1128/aem.67.5.2276-2283.2001
• Publication Date: 2002-07-27T10:00:58Z
• Authors: Peter L. Møller; Flemming Jørgensen; Ole C. Hansen; Søren M. Madsen; Peter Stougaard
• Keywords: Bifidobacterium bifidum; Galactosidases; Heterologous expression

ABSTRACT Three β-galactosidase genes from Bifidobacterium bifidum DSM20215 and one gene infantis DSM20088 were isolated characterized. The three B. β-galactosidases exhibited a low degree of amino acid sequence similarity to each other previously published classified as family 2 glycosyl hydrolases. Likewise, the was distantly related enzymes 42 One , termed BIF3, is most probably an extracellular enzyme, since it contained signal which cleaved off during heterologous expression enzyme in Escherichia coli . Other exceptional features BIF3 (i) monomeric structure active comprising 1,752 residues (188 kDa) (ii) molecular organization into N-terminal domain C-terminal galactose binding domain. two multimeric, intracellular with masses similar typical hydrolases, respectively. Despite differences size, composition, sequence, all four highly specific for hydrolysis β- d -galactosidic linkages, able transgalactosylate lactose substrate.