An integrated proteomic and physiological approach to understand the adhesion mechanism of the probiotic Lactobacillus reuteri Lb2 BM DSM 16143

The adhesion ability of the probiotic Lactobacillus reuteri Lb2 BM DSM 16143 was tested to both enterocyte-like Caco-2 cells and to extracellular matrix proteins (laminin, fibronectin and collagen I and IV). The adhesiveness was lost after an alkaline treatment known to release moonlighting proteins from lactobacillar cell surface. To characterize the putative adhesive molecules, a 2-DE experiment in the pI range 4-7 was performed on the extracellular proteins. The expression of several moonlighting proteins involved in adhesion (i.e. GAPDH, EF-Tu, phosphoglycerate kinase) was demonstrated. Some of the identified adhesins were able to bind plasminogen (Plg), but did not convert it into plasmin (Plm), in absence of exogenous activators. This indicates that the moonlighting proteome of L. reuteri Lb2 BM DSM 16143 can contribute to adhesion processes.