Peptidoglycan biosynthesis in Escherichia coli: variations in the metabolism of alanine and D-alanyl-D-alanine

J Gen Microbiol. 1992 Aug;138 Pt 8:1751-7. doi: 10.1099/00221287-138-8-1751.


The in vivo functioning of the alanine/D-alanyl-D-alanine pathway of Escherichia coli was investigated by determining precursor pool levels and specific enzyme activities under various growth conditions. Cells grown on D- or L-alanine showed several remarkable features compared with cells grown on other carbon sources: 10-fold higher values of the D-alanyl-D-alanine and the UDP-MurNAc-pentapeptide pools, a 240-fold increase of the alanine racemase activity, and the absence of bacteriolysis after treatment with D-cycloserine at high concentrations (50 micrograms ml-1). In cells grown on glucose, D-cycloserine (1 micrograms ml-1) led to depletion of the D-alanyl-D-alanine pool and to lysis, which was efficiently antagonized by chloramphenicol. A threefold increase of the dipeptide pool was observed when cells were treated with chloramphenicol alone. The alanine racemase activity was lowest in glucose-grown cells and the D-alanine:D-alanine ligase and D-alanyl-D-alanine-adding activities were the same whatever the carbon source. Molecular masses of 53-56 kDa and 56-60 kDa were estimated for the partially purified inducible alanine racemase and D-alanine:D-alanine ligase respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alanine / metabolism*
  • Chloramphenicol / pharmacology
  • Cycloserine / pharmacology
  • Dipeptides / metabolism*
  • Escherichia coli / enzymology
  • Escherichia coli / growth & development
  • Escherichia coli / metabolism*
  • Kinetics
  • Peptidoglycan / biosynthesis*


  • Dipeptides
  • Peptidoglycan
  • alanylalanine
  • Chloramphenicol
  • Cycloserine
  • Alanine