title: Cell wall monoglycine cross-bridges and methicillin hypersusceptibility in a femAB null mutant of methicillin-resistant Staphylococcus aureus.
abstract: The femAB operon is involved in the formation of the characteristic pentaglycine side chain of the staphylococcal peptidoglycan. Allele replacement of the femAB operon with the tetracycline resistance determinant tetK in a methicillin-resistant Staphylococcus aureus strain resulted in impaired growth, methicillin hypersusceptibility, and lysostaphin resistance. The usual pentaglycine cross-bridges were replaced by monoglycine bridges exclusively, and cross-linking of the peptidoglycan strands was drastically reduced. Complementation of the femAB null mutant by either femA or femAB resulted in the extension of the cross-bridges to a triglycine or a pentaglycine, respectively. This finding suggests that FemA is responsible for the formation of glycines 2 and 3, and FemB is responsible for formation of glycines 4 and 5, of the pentaglycine side chain of the peptidoglycan precursor. Moreover, it can be deduced that addition of the first glycine must occur by a femAB-independent mechanism.
authors.affiliation: Institute of Medical Microbiology, University of Zürich, Switzerland.
authors.forename: A M
authors.initials: AM
authors.lastname: Strandén
authors.forename: K
authors.initials: K
authors.lastname: Ehlert
authors.forename: H
authors.initials: H
authors.lastname: Labischinski
authors.forename: B
authors.initials: B
authors.lastname: Berger-Bächi
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002473:Cell Wall / Q000737:chemistry; D005816:Genetic Complementation Test; D005998:Glycine / Q000032:analysis / Q000737:chemistry*; D008248:Lysostaphin / Q000494:pharmacology; D008712:Methicillin / Q000494:pharmacology*; D016106:Methicillin Resistance / Q000235:genetics; D009154:Mutation; D010406:Penicillins / Q000494:pharmacology*; D010457:Peptidoglycan / Q000737:chemistry; D011487:Protein Conformation; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C096686:FemA protein, Bacteria; C102928:FemB protein, Staphylococcus epidermidis; D010406:Penicillins; D010457:Peptidoglycan; D008248:Lysostaphin; D008712:Methicillin; D005998:Glycine