Functionality of the S-layer protein from the probiotic strain Lactobacillus helveticus M92

Abstract

The objective of this study was the characterisation of the S-layer protein (SlpA) and its functional role in the probiotic activity of Lactobacillus helveticus M92. SlpA was isolated and identified by SDS-PAGE LC-MS/MS analysis. The slpA gene encoding the SlpA from L. helveticus M92 was sequenced and compared with other well characterised slpA genes. Sequence similarity searches revealed high homology with the SlpA of Lactobacillus strains. Purified SlpA showed significantly better immunomodulatory effects in orally immunised mice than L. helveticus M92 cells after SlpA removal. SlpA is involved in the autoaggregation of L. helveticus M92 cells and coaggregation of L. helveticus M92 with S. Typhimurium FP1 as these processes were negatively affected after SlpA removal from the cell surface. Therefore, the influence of oral treatment with L. helveticus M92 on an oral infection of mice by S. Typhimurium FP1 was investigated. Following the oral immunization of mice, with viable L. helveticus M92 and S. Typhimurium FP1 cells, the concentration in the luminal contents of total S-IgA and specific anti-Salmonella S-IgA antibodies, from all immunized mice was significantly higher compared to the control group or a group of mice infected only with S. Typhimurium FP1. These results demonstrate that the observed reduced infection by S. Typhimurium FP1 in mice with L. helveticus M92 is associated with competitive exclusion in the intestinal tract and enhanced immune protection conferred by the L. helveticus M92 and its SlpA.

S-Layer Protein Mediates the Stimulatory Effect of Lactobacillus helveticus MIMLh5 on Innate Immunity

“…For instance, it was shown that the Slayer protein from L. acidophilus ATCC 4356 T reduced Salmonella enterica serovar Typhimurium FP1-induced apoptosis in Caco-2 cells, and this effect was dependent on the inhibition of caspase-3 activation (41). In another study, the oral immunization of mice with the purified SlpA from L. helveticus M92 induced an increase in total levels of serum IgG, IgM, and IgA (42).…”

Role of S-layer proteins in bacteria

“…Therefore, the involvement of SLP in this process has been particularly studied for bacterial strains with potentiality as probiotics. In fact, the removal of SLP with 5 M LiCl reduces the autoaggregation ability of different lactobacilli such as Lactobacillus acidophilus ATCC 4356 (Kos et al 2003), L. kefiri CIDCA 8321 (Garrote et al 2004) and L. helveticus M92 (Beganović et al 2011). However, the strong autoaggregating phenotype of L. crispatus ZJ001 could be related to other cell surface components than SLP, since it is not markedly affected by treatment with LiCl (Chen et al 2007).…”

Lactobacillus helveticus MIMLh5-Specific Antibodies for Detection of S-Layer Protein in Grana Padano Protected-Designation-of-Origin Cheese

“…A similarity search using the deduced amino acid sequence of the L. helveticus MIMLh5 S-layer protein (EMBL database accession number HE993893) employing the algorithm BLASTP (33) revealed a high level of sequence homology to the other L. helveticus S-layer proteins (11) and to L. acidophilus S-layer proteins (8,24) (Fig. 1).…”

“…It has been documented that immunomodulatory properties of Lactobacillus spp. (e.g., Lactobacillus acidophilus NCFN [8,9], Lactobacillus brevis ATCC 8287 [10], and L. helveticus strain M92 [11]) are due to their surface layer (S-layer) protein. Recently it was demonstrated that the immunostimulatory properties of L. helveticus MIMLh5 are mainly mediated by its S-layer protein as well (12).…”