MafB constitutes a family of secreted toxins in pathogenic Neisseria species, probably involved in interbacterial competition [1]. Genes immediately downstream of mafB encode a specific immunity protein (MafI). MafB proteins exhibit a signal peptide sequence, a N-terminal conserved domain and a C-terminal variable region. Toxic domains identified at the C terminus include Pfam:PF15542, Pfam:PF14437, Pfam:PF15524, and Pfam:PF14436.

1: A new family of secreted toxins in pathogenic Neisseria species. Jamet A, Jousset AB, Euphrasie D, Mukorako P, Boucharlat A, Ducousso A, Charbit A, Nassif X; PLoS Pathog. 2015;11:e1004592. PMID:25569427