A novel alpha-galactosidase from I'ifidobacterium bifidum with transgalactosylating properties: gene molecular cloning and heterologous expression

Goulas, T., Goulas, A., Tzortzis, G. and Gibson, G. R. (2009) A novel alpha-galactosidase from I'ifidobacterium bifidum with transgalactosylating properties: gene molecular cloning and heterologous expression. Applied Microbiology and Biotechnology, 82 (3). pp. 471-477. ISSN 0175-7598 doi: 10.1007/s00253-008-1750-5

Abstract/Summary

A genomic library of Bifidobacterium bifidum (NCIMB 41171) DNA was constructed in Escherichia coli RA11r (melA(-)B(+)) and one alpha-galactosidase encoding gene was isolated. Conceptual translation combined with insertional mutagenesis analysis indicated an open reading frame (ORF) of 759 amino acid (aa) residues encoding an alpha-galactosidase (named as MelA) of 82.8 kDa. Partial purification and characterisation showed that the enzyme had an apparent native molecular mass of a parts per thousand 243 kDa and a subunit size of a parts per thousand 85 kDa. The enzyme belongs to glycosyl hydrolases 36 family with high aa sequence similarities (a parts per thousand 73%) to other known alpha-galactosidases of bifidobacterial origin. Under optimum pH conditions for activity (pH 6.0) and high melibiose concentration (40% w/v), the enzyme was able to form oligosaccharides with degree of polymerisation (DP) a parts per thousand yen3 at higher concentration than DP = 2, with a total yield of 20.5% (w/w).