Surface Glycosaminoglycans Protect Eukaryotic Cells against Membrane-Driven Peptide Bacteriocins

Abstract

e Enzymatic elimination of surface glycosaminoglycans or inhibition of their sulfation provokes sensitizing of HT-29 and HeLa cells toward the peptide bacteriocins nisin A, plantaricin C, and pediocin PA-1/AcH. The effect can be partially reversed by heparin, which also lowers the susceptibility of Lactococcus lactis to nisin A. These data indicate that the negative charge of the glycosaminoglycan sulfate residues binds the positively charged bacteriocins, thus protecting eukaryotic cells from plasma membrane damage. Bacteriocins are antimicrobial proteins produced by bacteria (1). Special attention has been devoted to peptides of between 20 and 40 amino acids produced by lactic acid bacteria (LAB) because they are usually resistant to boiling and extreme pH levels, which facilitates their use as preservatives in fermented foods (2). These peptides are divided into two major groups; class I is composed of molecules containing posttranslationally dehydrated serine and threonine residues and thioether linkages of these with neighboring cysteines to form lanthionine and 3-methyl-lanthionine, respectively, which is why they are termed "lantibiotics" (3, 4). Class II bacteriocins are composed of unmodified amino acids (2). These two classes are further subdivided depending on their secondary structure, the number of peptides that form the antimicrobial, and the spectrum of susceptible bacteria. These bactericidal peptides usually insert into the plasma membrane, polymerize there, and produce a pore, thus abolishing the membrane potential and inducing cytoplasmic solute leakage (5). These effects may be preceded by the recognition of membrane components, such as lipids I to IV, which results in the interruption of cell wall formation as well (4,6,7).LAB bacteriocins are consumed with fermented foods because the microbial starters produce them in the food matrix. Based on this, nisin A and pediocin PA-1/AcH have been authorized for use as food preservatives (8). Moreover, LAB are part of the autochthonous microbiota and are believed to produce bacteriocins in situ. However, there have been no reports on human or animal toxicity attributable to bacteriocins, in spite of the fact that the plasma membrane is an essential part of the eukaryotic cell. The lack of toxicity of LAB bacteriocins might be due to their susceptibility to digestive proteinases or to adsorption to food components. However, nisin has been intraperitoneally injected to combat experimental infections in mice with no secondary effects (9, 10). This suggests that peptide bacteriocins are unable to open pores in the eukaryotic cell membrane. Alternatively, they might not be able to reach the membrane because the eukaryotic glycocalyx may act as a barrier, as do the lipopolysaccharides of Gramnegative bacteria (11).Proteoglycans are part of the eukaryotic glycocalyx. They are composed of a protein stem and sulfated polysaccharide branches, called glycosaminoglycans (GAGs), that give a net negative charge to the polymer (12) and might help in blocking bacte...

Preclinical studies of toxicity and safety of the AS-48 bacteriocin

“…The resistance to AS-48 observed in eukaryotic cells was not unexpected, since eukaryotic membranes lack negatively charged lipids and contain cholesterol. Other studies have described the binding of positively charged bacteriocins by negatively charged glycosaminoglycan sulphate residues present in the proteoglycans of the eukaryotic glycocalyx, which protects eukaryotic cells against membrane damage [52]. However, in some eukaryotic organisms, such as parasites with negatively charged membranes (i.e.…”

Bacteriocins as Potential Anticancer Agents

“…Thus, this study shows the role of glycosylated membrane proteins in plnA-induced membrane permeabilization. The contrasting results were obtained in another study, wherein the effects of bacteriocins pln C, nisin A and pediocin-1/AcH were tested for their cytotoxicities against cancer cell lines HeLa and HT29 ( Martín et al, 2015 ). All the three bacteriocins tested at concentrations 1 and 10 μg had no cytotoxic effects against the cell lines HT29 and HeLa; however, enzymatic treatment (chondroitinase ABC and heparinase I, II, III) of the cell lines prior to bacteriocin addition resulted in loss in cell viabilities by almost 70% as shown by trypan blue assay.…”

“…The rapid killing induced by cytotoxic bacteriocins might indicate the non-receptor-mediated mode of action. The membrane surface glycoproteins and glycosaminoglycans were shown to be the cancer cell targets at least in case of plnA ( Sand et al, 2013 ); however, in case of other bacteriocins, such as nisin A, plnC and pediocin glycosaminoglycans appeared to prevent the cytotoxic action on the cancer cells ( Martín et al, 2015 ). Further studies are required to substantiate the role of surface molecules in their interaction with other cytotoxic bacteriocins.…”

An Extensive Review on Production, Purification, and Bioactive Application of Different Classes of Bacteriocin

“…The cytotoxic effects completely changed when a high concentration of plnC was used (Turner et al 1999). In addition, plnC did not show any cytotoxic activity against HT29 and HeLa cell lines at variable concentrations (Martín et al 2015).…”