Both IIC and IID Components of Mannose Phosphotransferase System Are Involved in the Specific Recognition between Immunity Protein PedB and Bacteriocin-Receptor Complex.

Wanli Zhou,Guohong Wang,Fazheng Ren,Yanling Hao,Chunmei Wang,Willem van Schaik

doi:10.1371/journal.pone.0164973

Abstract

Upon exposure to exogenous pediocin-like bacteriocins, immunity proteins specifically bind to the target receptor of the mannose phosphotransferase system components (man-PTS IIC and IID), therefore preventing bacterial cell death. However, the specific recognition of immunity proteins and its associated target receptors remains poorly understood. In this study, we constructed hybrid receptors to identify the domains of IIC and/or IID recognized by the immunity protein PedB, which confers immunity to pediocin PA-1. Using Lactobacillus plantarum man-PTS EII mutant W903, the IICD components of four pediocin PA-1-sensitive strains (L. plantarum WQ0815, Leuconostoc mesenteroides 05–43, Lactobacillus salivarius REN and Lactobacillus acidophilus 05–172) were respectively co-expressed with the immunity protein PedB. Well-diffusions assays showed that only the complex formed by LpIICD from L. plantarum WQ0815 with pediocin PA-1 could be recognized by PedB. In addition, a two-step PCR approach was used to construct hybrid receptors by combining LpIIC or LpIID recognized by PedB with the other three heterologous IID or IIC compounds unrecognized by PedB, respectively. The results showed that all six hybrid receptors were recognized by pediocin PA-1. However, when IIC or IID of L. plantarum WQ0815 was replaced with any corresponding IIC or IID component from L. mesenteroides 05–43, L. salivarius REN and L. acidophilus 05–172, all the hybrid receptors could not be recognized by PedB. Taken altogether, we concluded that both IIC and IID components of the mannose phosphotransferase system play an important role in the specific recognition between the bacteriocin-receptor complex and the immunity protein PedB.

Highlights

Bacteriocins, a class of antimicrobial peptides that are produced by bacteria, can inhibit growth or kill bacteria, while having diverse spectra of activity, i.e. from targeting only strains that are closely related to the producer strains or to a broader range of bacteria [1]
The results indicated that the immunity protein PedB could only recognize the complex formed by protein IICD from L. plantarum WQ0815 with pediocin PA-1 and could not recognize the complex formed by proteins IICD from L. mesenteroides 05–43, L. salivarius REN or L. acidophilus 05–172 with pediocin PA-1
We co-expressed immunity protein PedB with receptor IICD from L. plantarum WQ0815, L. mesenteroides 05–43, L. salivarius REN or L. acidophilus 05–172 in the host W903

Summary

Introduction

Bacteriocins, a class of antimicrobial peptides that are produced by bacteria, can inhibit growth or kill bacteria, while having diverse spectra of activity, i.e. from targeting only strains that are closely related to the producer strains or to a broader range of bacteria [1]. Pediocin-like bacteriocins are typically characterized by the presence of a conserved YGNGVXCXXXXCXV peptide motif within their N-terminal domains and by a strong inhibitory effect on Listeria [2]. Pediocin-like bacteriocins contain two domains: a cationic N-terminal domain and a more hydrophobic C-terminal domain determining the target cell specificity [3]. The strong inhibitory effect of pediocin-like bacteriocins on food pathogens, such as Listeria, suggests multiple applications as antimicrobials in food and feed industry [4]. Immunity proteins show remarkably high degrees of specificity to the bacteriocin they recognize, some of these immunity proteins may provide immunity to other pediocin-like bacteriocins [6]. The C-terminal domains of pediocin-like immunity proteins recognize the C-terminal hairpin domain of bacteriocins, resulting in immunity to bacteriocins [7, 8]. Sprules and colleagues suggested that the hydrophobic pocket within the C-terminal domain of the immunity proteins may be attracting the immunity proteins to the surface of the cell membrane [9]

Methods

Results

Conclusion