Biodiversity-Based Identification and Functional Characterization of the Mannose-Specific Adhesin ofLactobacillus plantarum

Abstract

Lactobacillus plantarum is a frequently encountered inhabitant of the human intestinal tract, and some strains are marketed as probiotics. Their ability to adhere to mannose residues is a potentially interesting characteristic with regard to proposed probiotic features such as colonization of the intestinal surface and competitive exclusion of pathogens. In this study, the variable capacity of 14 L. plantarum strains to agglutinate Saccharomyces cerevisiae in a mannose-specific manner was determined and subsequently correlated with an L. plantarum WCFS1-based genome-wide genotype database. This led to the identification of four candidate mannose adhesin-encoding genes. Two genes primarily predicted to code for sortase-dependent cell surface proteins displayed a complete gene-trait match. Their involvement in mannose adhesion was corroborated by the finding that a sortase (srtA) mutant of L. plantarum WCFS1 lost the capacity to agglutinate S. cerevisiae. The postulated role of these two candidate genes was investigated by gene-specific deletion and overexpression in L. plantarum WCFS1. Subsequent evaluation of the mannose adhesion capacity of the resulting mutant strains showed that inactivation of one candidate gene (lp_0373) did not affect mannose adhesion properties. In contrast, deletion of the other gene (lp_1229) resulted in a complete loss of yeast agglutination ability, while its overexpression quantitatively enhanced this phenotype. Therefore, this gene was designated to encode the mannose-specific adhesin (Msa; gene name, msa) of L. plantarum. Domain homology analysis of the predicted 1,000-residue Msa protein identified known carbohydrate-binding domains, further supporting its role as a mannose adhesin that is likely to be involved in the interaction of L. plantarum with its host in the intestinal tract.

Lectin Microarray Reveals Binding Profiles of Lactobacillus casei Strains in a Comprehensive Analysis of Bacterial Cell Wall Polysaccharides

“…Various factors produced by LAB have been proposed to actively interact with mammalian host cells (12). For example, soluble proteins produced by probiotic bacteria are known to regulate survival and growth of intestinal epithelial cells (11,18,30). Although the cell surface components of LAB such as S-layer proteins, LTA, WTA, and PSs are proposed to be immune modulators (21), the active components directly involved in immune modulation and the molecular nature of these recognition processes are largely unknown.…”

The predicted secretome of Lactobacillus plantarum WCFS1 sheds light on interactions with its environment

“…Of the 12 proteins identified as putative adhesion factors, ten proteins contain an LPxTG-like peptidoglycan anchor. One of these (lp_1229; msa) has been experimentally determined to encode a mannose-specific adhesin (Pretzer et al, 2005), which is proposed to fulfil a key role in reducing pathogenic efficacy of Escherichia coli strains through a competitive exclusion mechanism (Adlerberth et al, 1996;Pretzer et al, 2005).…”

“…polysaccharides), nutrient uptake and adherence to host cells (Buck et al, 2005;Kawai et al, 2006;Roos & Jonsson, 2002). For example, the protein Msa of L. plantarum has been shown to be a mannose-specific adhesin (Pretzer et al, 2005). Extracellular proteins are often large proteins consisting of many modules or domains (Bork, 1991).…”

Functional Characterization of a Mucus-Specific LPXTG Surface Adhesin from Probiotic Lactobacillus rhamnosus GG

“…Thus far, the precise molecular mechanisms that differentiate the colonization ability between autochthonous and allochthonous intestinal lactobacilli remain undefined (42), although they are likely to be partly dependent on a diverse range of cell surface adhesion molecule-mediated interactions with the host intestinal mucosa. With that being said, there are a growing number of reports in the literature that indicate that lactobacillar adherence to the intestinal mucosal layer is mediated by surface proteins with a mucus-binding capacity (15,21,22,25,30,32,33,41). Moreover, homology-driven genome mining in several Lactobacillus spp.…”