Abstract
By whole-genome sequencing of resistant mutants, a putative receptor for plantaricin JK, a two-peptide bacteriocin produced by some Lactobacillus plantarum strains, was identified in Lactobacillus plantarum NCFB 965 and Weissella viridescens NCFB 1655. The receptors of the two species had 66% identical amino acid sequences and belong to the amino acid-polyamine-organocation (APC) transporter protein family. The resistant mutants contained point mutations in the protein-encoding gene resulting in either premature stop codons, leading to truncated versions of the protein, or single amino acid substitutions. The secondary structure of the W. viridescens protein was predicted to contain 12 transmembrane (TM) helices, a core structure shared by most members of the APC protein family. The single amino acid substitutions that resulted in resistant strains were located in a confined region of the protein that consists of TM helix 10, which is predicted to be part of an inner membrane pore, and an extracellular loop between TM helix 11 and 12. By use of template-based modeling a 3D structure model of the protein was obtained, which visualizes this mutational hotspot region and further strengthen the hypothesis that it represents a docking site for plantaricin JK.
Highlights
Bacteriocins produced by lactic acid bacteria (LAB) are antimicrobial peptides that often kill closely related bacteria by inducing membrane leakage [1]
By whole-genome sequencing of plantaricin JK-resistant mutants of W. viridescens NCFB 1655, Oppegård et al recently identified a member of the amino acid-polyamine-organocation (APC) family of transport proteins as a putative plantaricin JK-receptor [20]
An APC protein family member was identified in both L. plantarum and W. viridescens as the putative receptor for plantaricin JK, and the structure of a possible bacteriocin docking site in this transporter was investigated using bioinformatics tools for prediction of TM helices and their orientation in the membrane and by template-based modeling of the 3D structure
Summary
Bacteriocins produced by lactic acid bacteria (LAB) are antimicrobial peptides that often kill closely related bacteria by inducing membrane leakage [1]. By whole-genome sequencing of plantaricin JK-resistant mutants of W. viridescens NCFB 1655, Oppegård et al recently identified a member of the amino acid-polyamine-organocation (APC) family of transport proteins as a putative plantaricin JK-receptor [20].
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