FemABX peptidyl transferase (IPR003447)

Short name: FEMABX

Overlapping homologous superfamilies

Family relationships


The entry represents the FemABX peptidyl transferase family.

FemABX peptidyl transferases catalyse the incorporation of amino acid(s) into the interchain peptide bridge of peptidoglycan using aminoacyl-tRNA as the amino acid donor, a reaction involved in the synthesis of the bacterial cell wall. The femABX enzymes catalyse the addition of amino acids to a peptidoglycan precursor, which in most cases is a lipid-linked sugar pentapeptide or, alternatively, a soluble nucleotide precursor for W. viridescens femX. The resulting branched peptide chain consists of one to five amino acids and is cross-linked to a pentapeptide of a neighbouring disaccharide chain by a transpeptidase in the final step of peptidoglycan synthesis. The interchain peptide and the femABX enzymes for their synthesis are found in several Gram-positive bacteria and in some Gram-negative, mainly pathogenic species. The femABX transferases differ by type, position and number of amino acids that are incoporated into the interchain. Some femABX proteins function as immunity factors that protect producers of interpeptide-specific endopeptidases against their own products. In addition, the interpeptide plays an important role in cell separation and virulence [PMID: 11083873, PMID: 12604510, PMID: 12679335, PMID: 14962386].

Some proteins known to belong to the femABX peptidyl transferase family:

  • Staphylococcal femA and femB, factors essential for expression of methicillin resistance. FemA adds glycines 2 and 3 of the pentaglycine interpeptide, while femB adds glycines 4 and 5.
  • Staphylococcal fmhB (for fem homolog) or femX, which incorporates the first glycine of the pentaglycine interchain peptide in peptidoglycan.
  • Weissella viridescens femX, which catalyzes the transfer of an L-alanine from Ala-tRNA to the epsilon-amino group of L-lysine of UDP-MurNAc pentapeptide [PMID: 12679335, PMID: 14962386].
  • Streptococcus pneumoniae fibA/murM and fibB/murN, which synthesize branched structured cell wall muropeptides that are strain-specific.
  • Staphylococcus capitis epr (endopeptidase resistance), which renders the cells resistant to glycylglycine endopeptidase by increasing the serine content and decreasing the glycine content of the interpeptide chains.

GO terms

Biological Process

GO:0044038 cell wall macromolecule biosynthetic process

Molecular Function

GO:0016755 transferase activity, transferring amino-acyl groups

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles