Characterization of MabA, a modulator of Lactobacillus rhamnosus GG adhesion and biofilm formation

Abstract

The probiotic Lactobacillus rhamnosus GG, first isolated from healthy human gut microbiota, has been reported to adhere very well to components of the intestinal mucosa, thereby enabling transient colonization of the gastrointestinal tract (GIT). In a search for the genes responsible for the good adherence capacity of this strain, a genomic region encoding a protein with homology to putative adhesion proteins (LGG-01865) and its putative regulator (LGG-01866) was identified. The sequence of the L. rhamnosus GG LGG-01865 encodes a polypeptide of 2419 amino acid residues containing 26 repetitive DUF1542 domains and a C-terminal LPxTG cell wall-anchoring motif. Phenotypic analyses of a dedicated LGG-01865 knockout mutant revealed a reduced biofilm formation capacity on abiotic surfaces and decreased adhesion to intestinal epithelial cells and tissues of the murine GIT. This suggests a modulating role for LGG-01865 in L. rhamnosus GG-host interactions. Therefore, we propose a new name for LGG-01865, i.e. MabA, modulator of adhesion and biofilm. Expression analysis indicated that LGG-01866 plays a conditional role in the regulation of LGG-01865 expression, i.e. when cells are grown under conditions of sugar starvation. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.