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Journal of Bacteriology, August 2007, p. 5929-5936, Vol. 189, No. 16
0021-9193/07/$08.00+0     doi:10.1128/JB.00159-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Binding of Human Plasminogen to Bifidobacterium

Department of Pharmaceutical Sciences, CIRB-Center for Biotechnology, University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy,¹ University of Würzburg, Research Center for Infectious Diseases, Röntgenring 11, D-97070 Würzburg, Germany,² Department of Experimental Pathology, Via S. Giacomo 14, 40126 Bologna, Italy,³ Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany⁴

Received 31 January 2007/ Accepted 29 May 2007

Bifidobacteria constitute up to 3% of the total microbiota and represent one of the most important health-promoting bacterial groups of the human intestinal microflora. The presence of Bifidobacterium in the human gastrointestinal tract has been directly related to several health-promoting activities; however, to date, no information about the specific mechanisms of interaction with the host is available. In order to provide some insight into the molecular mechanisms involved in the interaction with the host, we investigated whether Bifidobacterium was able to capture human plasminogen on the cell surface. By using flow cytometry, we demonstrated a dose-dependent human plasminogen-binding activity for four strains belonging to three bifidobacterial species: Bifidobacterium lactis, B. bifidum, and B. longum. The binding of human plasminogen to Bifidobacterium was dependent on lysine residues of surface protein receptors. By using a proteomic approach, we identified five putative plasminogen-binding proteins in the cell wall fraction of the model strain B. lactis BI07. The data suggest that plasminogen binding to B. lactis is due to the concerted action of a number of proteins located on the bacterial cell surface, some of which are highly conserved cytoplasmic proteins which have other essential cellular functions. Our findings represent a step forward in understanding the mechanisms involved in the Bifidobacterium-host interaction.

Published ahead of print on 8 June 2007.

This article has been cited by other articles:

• Candela, M., Miccoli, G., Bergmann, S., Turroni, S., Vitali, B., Hammerschmidt, S., Brigidi, P. (2008). Plasminogen-dependent proteolytic activity in Bifidobacterium lactis. Microbiology 154: 2457-2462 [Abstract] [Full Text]