Proteomics for the Investigation of Surface-Exposed Proteins in Probiotics

Abstract

Probiotics are commensal microorganisms that are present in the intestinal tract and in many fermented foods and positively affect human health, promoting digestion and uptake of dietary nutrients, strengthening intestinal barrier function, modulating immune response, and enhancing antagonism toward pathogens. The proteosurfaceome, i.e., the complex set of proteins present on the bacterial surface, is directly involved as leading actor in the dynamic communication between bacteria and host. In the last decade, the biological relevance of surface-exposed proteins prompted research activities exploiting the potentiality of proteomics to define the complex network of proteins that are involved in the molecular mechanisms at the basis of the adaptation to gastrointestinal environment and the probiotic effects. These studies also took advantages of the recent technological improvements in proteomics, mass spectrometry and bioinformatics that triggered the development of ad hoc designed innovative strategies to characterize the bacterial proteosurfaceome. This mini-review is aimed at describing the key role of proteomics in depicting the cell wall protein architecture and the involvement of surface-exposed proteins in the intimate and dynamic molecular dialogue between probiotics and intestinal epithelial and immune cells.

Postbiotics-parabiotics: the new horizons in microbial biotherapy and functional foods

“…The cell surface proteome of bacterial architecture plays a crucial role in exhibiting the dynamic molecular mechanism of probiotics. The bacterial surface proteins are classified in four categories, which include (i) proteins anchored to the cytoplasmic membrane by hydrophobic transmembrane domains (integral membrane proteins), (ii) lipoproteins (covalently attached to membrane lipids after cleavage of a signal peptide by signal peptidase II), (iii) proteins containing C-terminal LPXTG-like motif and covalently attached to peptidoglycan by sortases, and (iv) non-covalently bound proteins associated with cell wall by weak interactions (van der Waals forces, hydrogen or ion bonds) (LysM proteins, WXL proteins, GW proteins, proteins with choline-binding domains) [84]. The well-characterized cell surface-associated proteins in probiotic bacteria include surface (S) layer protein, mucus binding protein, fibronectin-binding protein, sortase dependent binding protein, collagen-binding protein, and so on (Fig.…”

“…The enzymes (EDTA-lysozyme) and chemical chaotropic agents [lithium chloride, guanidinium hydrochloride, urea, and sodium dodecyl sulphate (SDS)] have been widely reported to shave the surface proteins [84]. The gel-based and non-gel based methods have been widely employed to characterize the extractable proteins (Fig.…”

Cell‐envelope proteinases from lactic acid bacteria: Biochemical features and biotechnological applications

“…For example, in depth studies of cell surface proteins on probiotics have yielded important information for understanding variations in dairy protein proteolysis and cheese ripening, virulence in Streptococcus sp. (Bethe et al., 2001; Bonifait et al., 2010), bacterial adhesion to host epithelial cells, triggering of mucus/anti‐inflammatory compound secretion by host gut cells, among others (Siciliano, Lippolis, & Mazzeo, 2019). Going forward, we anticipate that CEP research will mainly focus on the use of proteomics and biochemical assays to understand the so called “proteosurfaceome,” a term use to describe the complex surface proteins displayed on bacteria cells.…”

Deletion of S-Layer Associated Ig-Like Domain Protein Disrupts the Lactobacillus acidophilus Cell Surface

“…Probiotics are generally defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host" (Hill et al, 2014). Research has begun to hone in on the molecules and genes associated with these health-promoting properties chiefly to augment next-generation probiotic screening efforts (Lebeer et al, 2008;Siciliano et al, 2019). Of particular interest are extracellular proteins, such as surface-layers (S-layers), which can directly interact with and influence the host gastrointestinal tract (Kleerebezem et al, 2010;Lebeer et al, 2010).…”

“…As one of the most abundant molecules produced by the cell, Slps play pivotal roles in growth and survival, cell integrity, and interactions with the host and its immune system (Sleytr and Beveridge, 1999;Sara and Sleytr, 2000;Hynonen and Palva, 2013;Sleytr et al, 2014). S-layers can also act as scaffolds for the external display of auxiliary proteins and glycoproteins which confer supplementary functionalities (Fagan and Fairweather, 2014;Siciliano et al, 2019). The S-layer associated proteins (SLAPs) of L. acidophilus have been linked to diverse roles in cell division, intestinal adhesion, and host immunomodulation (Altermann et al, 2004;Johnson et al, 2013Johnson et al, , 2017Hymes et al, 2016;Johnson and Klaenhammer, 2016).…”