University of Wollongong
Browse

Crystal structure and site-directed mutagenesis of circular bacteriocin plantacyclin B21AG reveals cationic and aromatic residues important for antimicrobial activity

Download (3.31 MB)
journal contribution
posted on 2024-11-15, 17:59 authored by Mian Gor, Ben Vezina, Roisín McMahon, Gordon King, Santosh Panjikar, Bernd Rehm, Jennifer Martin, Andrew Smith
© 2020, The Author(s). Plantacyclin B21AG is a circular bacteriocin produced by Lactiplantibacillus plantarum B21 which displays antimicrobial activity against various Gram-positive bacteria including foodborne pathogens, Listeria monocytogenes and Clostridium perfringens. It is a 58-amino acid cyclised antimicrobial peptide, with the N and C termini covalently linked together. The circular peptide backbone contributes to remarkable stability, conferring partial proteolytic resistance and structural integrity under a wide temperature and pH range. Here, we report the first crystal structure of a circular bacteriocin from a food grade Lactobacillus. The protein was crystallised using the hanging drop vapour diffusion method and the structure solved to a resolution of 1.8 Å. Sequence alignment against 18 previously characterised circular bacteriocins revealed the presence of conserved charged and aromatic residues. Alanine substitution mutagenesis validated the importance of these residues. Minimum inhibitory concentration analysis of these Ala mutants showed that Phe8Ala and Trp45Ala mutants displayed a 48- and 32-fold reduction in activity, compared to wild type. The Lys19Ala mutant displayed the weakest activity, with a 128-fold reduction. These experiments demonstrate the relative importance of aromatic and cationic residues for the antimicrobial activity of plantacyclin B21AG and by extension, other circular bacteriocins sharing these evolutionarily conserved residues.

History

Citation

Gor, M., Vezina, B., McMahon, R. M., King, G. J., Panjikar, S., Rehm, B. H. A., Martin, J. L. & Smith, A. T. (2020). Crystal structure and site-directed mutagenesis of circular bacteriocin plantacyclin B21AG reveals cationic and aromatic residues important for antimicrobial activity. Scientific Reports, 10 (1), 1-16.

Journal title

Scientific Reports

Volume

10

Issue

1

Language

English

RIS ID

146101

Usage metrics

    Categories

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC