Intra- and extracellular beta-galactosidases from Bifidobacterium bifidum and B. infantis: molecular cloning, heterologous expression, and comparative characterization.

ABSTRACT: Three beta-galactosidase genes from Bifidobacterium bifidum DSM20215 and one beta-galactosidase gene from Bifidobacterium infantis DSM20088 were isolated and characterized. The three B. bifidum beta-galactosidases exhibited a low degree of amino acid sequence similarity to each other and to previously published beta-galactosidases classified as family 2 glycosyl hydrolases. Likewise, the B. infantis beta-galactosidase was distantly related to enzymes classified as family 42 glycosyl hydrolases. One of the enzymes from B. bifidum, termed BIF3, is most probably an extracellular enzyme, since it contained a signal sequence which was cleaved off during heterologous expression of the enzyme in Escherichia coli. Other exceptional features of the BIF3 beta-galactosidase were (i) the monomeric str

SUBMITTER: Moller PL 

PROVIDER: S-EPMC92867 | biostudies-literature | 2001 May

REPOSITORIES: biostudies-literature