This entry describes a rare family of small proteins, about 50 residues in length, that includes YydF from Bacillus subtilis and SAG 2028 from Streptococcus agalactiae 2603V/R. Mutational analysis and genomic context show that members of this family likely are modified by a (variably present) radical SAM enzyme, are exported by an ABC transporter, and may have antimicrobial or signalling properties (or both). The member from Bacillus subtilis induces the LiaRS two-component system [].
