The femAB operon codes for two nearly identical approximately 50-kDa proteins involved in the formation of the Staphylococcal pentaglycine interpeptide bridge in peptidoglycan [1]. These proteins are also considered as a factor influencing the level of methicillin resistance [2].

1: Specificities of FemA and FemB for different glycine residues: FemB cannot substitute for FemA in staphylococcal peptidoglycan pentaglycine side chain formation. Ehlert K, Schroder W, Labischinski H; J Bacteriol 1997;179:7573-7576. PMID:9393725

2: Molecular characterization of femA from Staphylococcus hominis and Staphylococcus saprophyticus, and femA-based discrimination of staphylococcal species. Vannuffel P, Heusterspreute M, Bouyer M, Vandercam B, Philippe M, Gala JL; Res Microbiol 1999;150:129-141. PMID:10209768

3: FemA, a host-mediated factor essential for methicillin resistance in Staphylococcus aureus: molecular cloning and characterization. Berger-Bachi B, Barberis-Maino L, Strassle A, Kayser FH; Mol Gen Genet 1989;219:263-269. PMID:2559314

4: Cell wall monoglycine cross-bridges and methicillin hypersusceptibility in a femAB null mutant of methicillin-resistant Staphylococcus aureus. Stranden AM, Ehlert K, Labischinski H, Berger-Bachi B; J Bacteriol 1997;179:9-16. PMID:8981974

5: Influence of femB on methicillin resistance and peptidoglycan metabolism in Staphylococcus aureus. Henze U, Sidow T, Wecke J, Labischinski H, Berger-Bachi B; J Bacteriol 1993;175:1612-1620. PMID:8383661