Molecular and biochemical properties of the S-layer protein from the wine bacterium Lactobacillus hilgardii B706

Abstract

Different strains of the genus Lactobacillus can be regularly isolated from must and wine samples. By various physiological activities, they can improve or reduce the wine quality. Lactobacillus hilgardii that is known to survive under harsh wine conditions is classified as a spoilage bacterium, e.g. due to the production of histamine. Many lactobacilli form an S-layer as the outermost cell wall component which has been found to facilitate the colonization of special ecological niches. A detailed understanding of the properties related to their S-layer proteins is necessary to improve the knowledge of the interactions between different bacterial cells and with the surrounding environments. The S-layer protein from the wine-related L. hilgardii strain B706 has been isolated and its gene sequence determined. The deduced amino acid sequence corresponds to a 41 kDa protein with an isoelectric point of 9.6 without additional posttranslational modifications after splitting off the leader peptide. The complete protein is organized in a 32 amino acids signal sequence for membrane translocation, a positively charged N-terminal domain that binds to the cell wall and a negatively charged C-terminal domain. When the S-layer was removed, the corresponding L. hilgardii B706 cells became more sensitive to bacteriolytic enzymes and some wine-related stress conditions. From a practical point of view, the S-layer may be considered as a target for the inhibition of food-spoiling lactobacilli.

Studies on Two Exoenzymes Which Lyse Wine-Spoiling Bacteria

“…It could, therefore, be concluded that the S-layer protein consists of two equal-sized domains, and only one of those is sensitive against the protease of S. albidoflavus B 578. A similar result was found in our previous study for the S-layer protein from a Lactobacillus hilgardii strain [22].…”

“…Some experimental data give hints that the proteases cleave peptide bonds in the peptidoglycan or the outer membrane of Gram-negative bacteria [41]. Another possible target are S-layer proteins, which comprise the outer cell border of many Archaea and Gram-positive bacteria, including lactic acid bacteria [22] [42] [43]. In this study, we found that the purified protease degrades S-layer proteins from L. brevis B 190, and previously, we demonstrated that the S-layer of Lactobacillus hilgardii B706 was degraded by the culture supernatant of S. albidoflavus B 578 [22].…”

“…S-layer proteins were isolated as described by Dohm et al [22]. The bacterial biomass from 500 ml cultures of L. brevis B 190 grown at 30˚C for two days was harvested by centrifugation (9000 × g, 4˚C) and washed twice with sterile deionized water.…”

Hypothetical Protein Avin_16040 as the S-Layer Protein of Azotobacter vinelandii and Its Involvement in Plant Root Surface Attachment

“…The bacterial S-layer protein was predicted to have a transmembrane helix and undergo a posttranslational modification by signal peptide excision (45,46). The Avin_16040 protein was also predicted to have a transmembrane helix at the N terminus preceded by an overlapping signal peptide of 20 amino acids.…”

Identification of multiple putative S-layer genes partly expressed by Lysinibacillus sphaericus JG-B53

“…A remarkable characteristic of S-layer proteins is their strong resistance to extreme environmental conditions such as high ionic strength, low pH and high temperature (Claus et al, 2002;Engelhardt & Peters, 1998), suggesting that they contribute to the stabilization and protection of the cells (Claus et al, 2005). S-layer proteins work as molecular sieves and molecule and ion traps, and have in particular the ability to selectively bind heavy metal ions (Dohm et al, 2011;Merroun et al, 2005;Raff, 2002;Sára & Sleytr, 1987).…”