This protein family includes the immunity protein YezG from Bacillus subtilis and similar sequences predominantly found in Firmicutes. YezG is the antitoxin component of a LXG toxin-antitoxin (TA) module that promote kin selection, mediate competition in biofilms, and drive spatial segregation of different strains, probably helping to avoid warfare between strains in biofilms [1]. It shows an alpha/beta structure with an antiparallel beta-sheet.

1: Diverse LXG toxin and antitoxin systems specifically mediate intraspecies competition in Bacillus subtilis biofilms. Kobayashi K; PLoS Genet. 2021;17:e1009682. PMID:34280190