Exploring interactions of the S-layer protein of Lactobacillus acidophilus ATCC4356

FINA MARTIN, JOAQUINA; ALLIEVI, MARIANA CLAUDIA; BARQUERO ANDREA; CUTINE AM; MARIÑO KV; PALOMINO MARIA MERCEDES; SOFIA ZANINI; RUZAL SANDRA M.

Parana

Congreso; SAIB 2018; 2018

SAIB

Surface layer (S-layer) proteins are the outermost cell envelope of some species of lactobacilli, and they have been involved in modulating the host immune system and inhibit pathogenic virus and bacteria adhesion. This attribute has made them interesting from a prophylactic point of view, to prevent infection. Here, we investigate interactions of purified S-layer proteins from Lactobacillus acidophilus ATCC 4356 cells, and chimerical GFP?S-layer fusion proteins containing different portions of the SlpA protein both with prokaryotic (peptidoglycan and lipoteichoic acids) and eukaryotic (mucin, fibronectin, collagen) macromolecules, as well as with viruses and bacterial, yeast and blood cells. The lectin capacity of S-layers was analysed by means of Dot blot analysis, hemagglutination, flow cytometry and solid phase assays. Our results show that the C-terminal portion of the S-layer protein recognizes carbohydrates, interacting with different glycoconjugates, being the LTA (lipoteichoic acids) and mannose-derived structures the preferred ligands. The interaction of the SlpA protein with viral particles was studied by means of a virulent activity test of herpes simplex virus type 1 (HSV-1), vesicular stomatitis virus (VSV), human adenovirus type 5 (AdV5) and bacteriophage J1. No virucidal activity was observed. However, interaction with viral particles enables to co-precipitate them with the protein after centrifugation, decreasing the viral titer without affecting bacteriophage titer, suggesting that S-layer proteins interact with glycosylated proteins of the virus. All together, these results may explain the pathogen exclusion effect reported for SlpA.