This subfamily family contains FosB, a fosfomycin resistant protein. FosB is a Mg(2+)-dependent L-cysteine thiol transferase. Fosfomycin inhibits the enzyme UDP-nacetylglucosamine-3-enolpyruvyltransferase (MurA), which catalyzes the first committed step in bacterial cell wall biosynthesis. FosB catalyzes the Mg(II) dependent addition of L-cysteine to the epoxide ring of fosfomycin, (1R,2S)-epoxypropylphosphonic acid, rendering it inactive. FosB is evolutionarily related to glyoxalase I and type I extradiol dioxygenases.