Adhesions of extracellular surface-layer associated proteins in Lactobacillus M5-L and Q8-L

Abstract

Surface-layer associated proteins (SLAP) that envelop Lactobacillus paracasei ssp. paracasei M5-L and Lactobacillus casei Q8-L cell surfaces are involved in the adherence of these strain to the human intestinal cell line HT-29. To further elucidate some of the properties of these proteins, we assessed the yields and expressions of SLAP under different incubation conditions. An efficient and selective extraction of SLAP was obtained when cells of Lactobacillus were treated with 5 M LiCl at 37°C in aerobic conditions. The SLAP of Lactobacillus M5-L and Q8-L in cell extracts were visualized by SDS-PAGE and identified by Western blotting with sulfo-N-hydroxysuccinimide-biotin-labeled HT-29 cells as adhesion proteins. Atomic force microscopy contact imaging revealed that Lactobacillus strains M5-L and Q8-L normally display a smooth, homogeneous surface, whereas the surfaces of M5-L and Q8-L treated with 5 M LiCl were rough and more heterogeneous. Analysis of adhesion forces revealed that the initial adhesion forces of 1.41 and 1.28 nN obtained for normal Lactobacillus M5-L and Q8-L strains, respectively, decreased to 0.70 and 0.48 nN, respectively, following 5 M LiCl treatment. Finally, the dominant 45-kDa protein bands of Lactobacillus Q8-L and Lactobacillus M5-L were identified as elongation factor Tu and surface antigen, respectively, by liquid chromatography-tandem mass spectrometry.

Purification of Lactobacillus acidophilus surface‐layer protein and its immunomodulatory effects on RAW264.7 cells

“…A) and homogeneous, whereas the surface of the cells treated with LiCl was uneven and heterogeneous (Fig. B) …”

“…2B). 23 To achieve pure SLP, we used Sephadex G-75 chromatography to purify crude SLP extracts that had been dissolved by PBS. One obvious elution peak appeared at approximately 28 min in the SLP elution profile (Fig.…”

The extracellular proteome of two Bifidobacterium species reveals different adaptation strategies to low iron conditions

“…Elongation factors have been found in the secretome lactobacilli and are involved in the adhesion Lactobacillus johnsonii to human intestinal cells and mucins [62, 63]. Their presence in the secretome and the high adhesion properties of both strains [64] suggests a similar role for these factors in bifidobacteria.…”

Extractable Bacterial Surface Proteins in Probiotic–Host Interaction

“…However, a thorough proteomic study of this extracted fraction evidenced other proteins, in addition to Slps, in L. acidophilus , for example, showing that Slps constitute an anchor for several other extractable surface-bound proteins called SLAPs ( Johnson et al, 2013 ). Such proteins, identified in Lactobacillus species, have different functions, including interaction with the host ( Johnson et al, 2013 , 2016 , 2017 ; Waśko et al, 2014 ; Zhang et al, 2016 ). In the absence of an S-layer, other non-covalently surface-bound proteins may exist and be extracted using chaotropic agents.…”

“…Accordingly, L. brevis ATCC 8287 surface layer shows a high affinity to laminin and to fibronectin, and its removal affects L. brevis adhesion to intestinal cells and to extracellular matrix proteins ( Hynönen et al, 2002 ; de Leeuw et al, 2006 ; Uroić et al, 2016 ). Extracted surface bound proteins from probiotic lactobacilli were shown by different authors to bind in vitro to host cells proteins and extracellular matrix ( Chen et al, 2007 ; Johnson-Henry et al, 2007 ; Carasi et al, 2014 ; Waśko et al, 2014 ; Prado Acosta et al, 2016 ; Zhang et al, 2016 ). However, such results should be considered with care, as Slps are poorly soluble, forming aggregates in aqueous environments, which renders interpretation of results difficult.…”