confers_resistance_to_antibiotic fosfomycin confers_resistance_to_antibiotic fosfomycin thiol transferase FosA FosA PDB:1NPB ARO:3000149 An enzyme that confers resistance to fosfomycin in Serratia marcescens by breaking the epoxide ring of the molecule. It depends on the cofactors Manganese (II) and Potassium and uses Glutathione (GSH) as the nucleophilic molecule. In Pseudomonas aeruginosa, FosA catalyzes the conjugation of glutathione to carbon-1 of fosfomycin, rendering it ineffective as an antibacterial drug. antibiotic_resistance