title: Characterization of the Maf family of polymorphic toxins in pathogenicNeisseria species.
abstract: In addition to harmless commensal species,Neisseriagenus encompasses two pathogenic species,N. meningitidis(the meningococcus) andN. gonorrhoeae(the gonococcus), which are responsible for meningitis and genital tract infections, respectively. Since the publication of the firstNeisseriagenome in 2000, the presence of several genomic islands (GI) comprisingmafgenes has been intriguing. These GIs account for approximately 2% of the genome of the pathogenicNeisseriaspecies and the function of the proteins encoded bymafgenes remained unknown. We showed thatmafgenes encode a functional toxin-immunity system where MafB is a toxin neutralized by an immunity protein named MafI. A strain can harbor several MafB/MafI modules with distinct toxic activities. MafB toxins are polymorphic toxins with a conserved N-terminal region and a variable C-terminal region. MafB N-terminal regions consist of a signal peptide and a domain named DUF1020 that is only found in the genusNeisseria. MafB C-terminal regions are highly polymorphic and encode toxic activities. We evidenced the presence of MafB in the culture supernatant of meningococcal cells and we observed a competitive advantage for a strain overexpressing a MafB toxin. Therefore, we characterized a highly variable family of toxin-immunity modules found in multiple loci in pathogenicNeisseriaspecies.
authors.affiliation: Instituto de Microbiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal. ; Institut Necker Enfants-Malades, 14 rue Maria Helena Vieira Da Silva, CS 61431, 75014 Paris, France. ; Université Paris Descartes; Sorbonne Paris Cité, Faculté de Médecine, Paris, France. ; INSERM, U1151, Paris, France. ; CNRS UMR 8253, Paris, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Jamet
authors.affiliation: Institut Necker Enfants-Malades, 14 rue Maria Helena Vieira Da Silva, CS 61431, 75014 Paris, France. ; Université Paris Descartes; Sorbonne Paris Cité, Faculté de Médecine, Paris, France. ; INSERM, U1151, Paris, France. ; CNRS UMR 8253, Paris, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Nassif
keywords: MafB; Neisseria; immunity gene; toxin