AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Møller, P. L.
Right arrow Articles by Stougaard, P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Møller, P. L.
Right arrow Articles by Stougaard, P.
Agricola
Right arrow Articles by Møller, P. L.
Right arrow Articles by Stougaard, P.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, May 2001, p. 2276-2283, Vol. 67, No. 5
0099-2240/01/$04.00+0   DOI: 10.1128/AEM.67.5.2276-2283.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.

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

Peter L. Møller,dagger Flemming Jørgensen, Ole C. Hansen, Søren M. Madsen, and Peter Stougaard*

Biotechnological Institute, DK-2970 Hørsholm, Denmark

Received 30 October 2000/Accepted 27 February 2001

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 structure of the active enzyme, comprising 1,752 amino acid residues (188 kDa) and (ii) the molecular organization into an N-terminal beta -galactosidase domain and a C-terminal galactose binding domain. The other two B. bifidum beta -galactosidases and the enzyme from B. infantis were multimeric, intracellular enzymes with molecular masses similar to typical family 2 and family 42 glycosyl hydrolases, respectively. Despite the differences in size, molecular composition, and amino acid sequence, all four beta -galactosidases were highly specific for hydrolysis of beta -D-galactosidic linkages, and all four enzymes were able to transgalactosylate with lactose as a substrate.

* Corresponding author. Mailing address: Biotechnological Institute, Kogle Allé 2, DK-2970 Hørsholm, Denmark. Phone: 45 45160444. Fax: 45 45160455. E-mail: pst{at}bioteknologisk.dk.

dagger Present address: Department of Dairy and Food Science, The Royal Veterinary and Agricultural University, DK-1958 Frederiksberg C, Denmark.

Applied and Environmental Microbiology, May 2001, p. 2276-2283, Vol. 67, No. 5
0099-2240/01/$04.00+0   DOI: 10.1128/AEM.67.5.2276-2283.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 2001 by the American Society for Microbiology. All rights reserved.