6WI6

Crystal structure of plantacyclin B21AG

Summary for 6WI6

• Entry DOI: 10.2210/pdb6wi6/pdb
• Descriptor: Plantacyclin B21AG, MALONATE ION (3 entities in total)
• Functional Keywords: circular bacteriocin, antimicrobial peptide, lactic acid bacteria, antimicrobial protein
• Biological source: Lactobacillus plantarum
• Total number of polymer chains: 2
• Total formula weight: 11481.34

Authors

Smith, A.T.,Gor, M.C.,Vezina, B.,McMahon, R.,King, G.,Panjikar, S.,Rehm, B.,Martin, J. (deposition date: 2020-04-08, release date: 2021-01-06, Last modification date: 2024-10-09)

Primary citation

Gor, M.C.,Vezina, B.,McMahon, R.M.,King, G.J.,Panjikar, S.,Rehm, B.H.A.,Martin, J.L.,Smith, A.T.
Crystal structure and site-directed mutagenesis of circular bacteriocin plantacyclin B21AG reveals cationic and aromatic residues important for antimicrobial activity.
Sci Rep, 10:17398-17398, 2020

PubMed Abstract: 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 PheAla and TrpAla mutants displayed a 48- and 32-fold reduction in activity, compared to wild type. The LysAla 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.

PubMed: 33060678
DOI: 10.1038/s41598-020-74332-1

Experimental method

X-RAY DIFFRACTION (1.8 Å)