title: Fratricide activity of MafB protein of N. meningitidis strain B16B6.
abstract: BACKGROUND
  Neisseria meningitidis is an inhabitant of the mucosal surfaces of the human nasopharynx. We recently demonstrated that the secreted meningococcal Two-partner secretion protein A (TpsA) is involved in interbacterial competition. The C-terminal end of the large TpsA protein contains a small toxic domain that inhibits the growth of target bacteria. The producing cells are protected from this toxic activity by a small immunity protein that is encoded by the gene immediately downstream of the tpsA gene. Further downstream on the chromosome, a repertoire of toxic modules, designated tpsC cassettes, is encoded that could replace the toxic module of TpsA by recombination. Each tpsC cassette is associated with a gene encoding a cognate immunity protein.
  
  
  RESULTS
  Blast searchers using the toxic domains of TpsA and TpsC proteins as queries identified homologies with the C-terminal part of neisserial MafB proteins, which, for the rest, showed no sequence similarity to TpsA proteins. On the chromosome, mafB genes are part of genomic islands, which include cassettes for additional toxic modules as well as genes putatively encoding immunity proteins. We demonstrate that a MafB protein of strain B16B6 inhibits the growth of a strain that does not produce the corresponding immunity protein. Assays in E. coli confirmed that the C-terminal region of MafB is responsible for toxicity, which is inhibited by the cognate immunity protein. Pull-down assays revealed direct interaction between MafB toxic domains and the cognate immunity proteins.
  
  
  CONCLUSIONS
  The meningococcal MafB proteins are novel toxic proteins involved in interbacterial competition.
authors.affiliation: Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands. J.A.arenasbusto@uu.nl.
authors.forename: Jesús
authors.initials: J
authors.lastname: Arenas
authors.affiliation: Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands. vincent.de.maat@gmail.com.
authors.forename: Vincent
authors.initials: V
authors.lastname: de Maat
authors.affiliation: Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands. catona.laura@gmail.com.
authors.forename: Laura
authors.initials: L
authors.lastname: Catón
authors.affiliation: Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands. m.krekorian@students.uu.nl.
authors.forename: Massis
authors.initials: M
authors.lastname: Krekorian
authors.affiliation: Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands. j.c.herreromartin@students.uu.nl.
authors.forename: Juan Cruz
authors.initials: JC
authors.lastname: Herrero
authors.affiliation: Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands. flavio.ferrara88@gmail.com.
authors.forename: Flavio
authors.initials: F
authors.lastname: Ferrara
authors.affiliation: Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands. J.P.M.Tommassen@uu.nl.
authors.forename: Jan
authors.initials: J
authors.lastname: Tommassen
mesh_terms: D001430:Bacteriocins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D051258:MafB Transcription Factor / Q000378:metabolism*; D050296:Microbial Viability / Q000187:drug effects*; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D001430:Bacteriocins; D004269:DNA, Bacterial; D051258:MafB Transcription Factor