- Taylor JD, Taylor G, Hare SA, Matthews SJ
- Structures of the DfsB Protein Family Suggest a Cationic, Helical Sibling Lethal Factor Peptide.
- J Mol Biol. 2016 Jan 21. pii: S0022-2836(16)00032-2. doi:, 10.1016/j.jmb.2016.01.013.
- Bacteria have developed a variety of mechanisms for surviving harsh environmental conditions, nutrient stress and overpopulation. Paenibacillus dendritiformis produces a lethal protein (Slf) that is able to induce cell death in neighbouring colonies and a phenotypic switch in more distant ones. Slf is derived from the secreted precursor protein, DfsB, after proteolytic processing. Here, we present new crystal structures of DfsB homologues from a variety of bacterial species and a surprising version present in the yeast Saccharomyces cerevisiae. Adopting a four-helix bundle decorated with a further three short helices within intervening loops, DfsB belongs to a non-enzymatic class of the DinB fold. The structure suggests that the biologically active Slf fragment may possess a C-terminal helix rich in basic and aromatic residues that suggest a functional mechanism akin to that for cationic antimicrobial peptides.