This family includes short bacterial and archaebacterial proteins thought to be antitoxin components of the a type II toxin-antitoxin (TA) system. This entry includes AF2212 from Archaeoglobus fulgidus which has sequence similarity with the AbrB superfamily of DNA-binding proteins, identified as antitoxins [1,2]. The secondary structure of AF2212 revealed at least three beta-strands that are most conserved in other AbrB superfamily members [2].

1: Toxin-antitoxin loci are highly abundant in free-living but lost from host-associated prokaryotes. Pandey DP, Gerdes K; Nucleic Acids Res. 2005;33:966-976. PMID:15718296

2: Comprehensive comparative-genomic analysis of type 2 toxin-antitoxin systems and related mobile stress response systems in prokaryotes. Makarova KS, Wolf YI, Koonin EV; Biol Direct. 2009;4:19. PMID:19493340