Delineation of key amino acid side chains and peptide domains for antimicrobial properties of divercin V41, a pediocin-like bacteriocin secreted by Carnobacterium divergens V41

Divercin V41 (DV41) is a class IIa bacteriocin produced by Carnobacterium d ivergens V41. This antilisterial peptide is homologous to pediocin PA-1 and contains two disulfide bonds. To establish the structure-activity relation ships of this specific family of bacteriocin, chemical modifications and en zymatic hydrolysis were performed on DV41. Alteration of the net charge of this cationic bacteriocin by succinylation and acetylation revealed that, i n a certain range, the electrostatic interactions were surprisingly not nec essary for the activity of DV41. Cleavage of DV41 by endoproteinase Asp-N r eleased two fragments N1[1-17] and N2[18-43] corresponding to the conserved hydrophilic N-terminal and the variable hydrophobic C-terminal sequences, respectively. Inhibitory assays showed that only the C-terminal fragment wa s active, and after trypsin cleavage at Lys42 or disulfide reduction it los t its inhibitory activity. These results suggested that both hydrophobicity and folding imposed by the Cys25-Cys43 disulfide bond were essential for a ntilisterial activity of the C-terminal hydrophobic peptide. Chemical oxida tion of tryptophan residues by N-bromosuccinimide demonstrated that these r esidues were crucial for inhibitory activity since modification of any one of them rendered DV41 inactive. On the contrary, only the modification of a ll the three tyrosine residues caused a total loss of antilisterial activit y. These latter results strengthened previous results suggesting that the N -terminal domain containing the YGNGV consensus sequence was not involved i n the binding of DV41 to a potential specific receptor on listerial cells.