title: Structures of the DfsB Protein Family Suggest a Cationic, Helical Sibling Lethal Factor Peptide.
abstract: 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.
authors.affiliation: Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Taylor
authors.affiliation: Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Taylor
authors.affiliation: Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Hare
authors.affiliation: Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom. Electronic address: s.j.matthews@imperial.ac.uk.
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Matthews
mesh_terms: D001419:Bacteria / Q000737:chemistry; D001430:Bacteriocins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D056507:Paenibacillus / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*
chemical_list: D001430:Bacteriocins; C000609270:IRC4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins
keywords: DfsB; Fratricide; bacteriocin; patterning; sporulation