Induction of beta-lactamase in Enterobacter cloacae.
beta-lactamase induction in Enterobacter cloacae, which is linked to peptidoglycan recycling, was investigated with use of high-performance liquid chromatography of cell wall fragments in genetically defined cells of Escherichia coli. After treatment of cells with beta-lactams, we detected in the periplasm an increase of D-tripeptide (N-acetylglucosaminyl-1,6 anhydro N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid), D-tetrapeptide (N-acetylglucosaminyl-1, 6 anhydro N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid -D-alanine), and a yet-unknown anhydromuropeptide. We identified this anhydromuramylpeptide by fast atom bombardment-mass spectrometry as anhydromuramyl-pentapeptide. The amount of these molecules did not alter after treatment with cell wall-active non beta-lactams. The transmembrane protein AmpG transports not only D-tripeptide but also D-pentapeptide into the cell. In the cytoplasm these molecules are degraded into the corresponding monosaccharide peptides M-tripeptide (N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid) and M-pentapeptide (N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid-alanine-D-alanine). These findings indicate that besides M-tripeptide and D-tripeptide, probably M-tetrapeptide, D-tetrapeptide, M-pentapeptide, and D-pentapeptide are also signal muropeptides for beta-lactamase induction.
University of Bonn, Germany.
B
B
Wiedemann
H
H
Dietz
D
D
Pfeifle
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall; D016972:Enterobacter cloacae / Q000201:enzymology* / Q000235:genetics; D004790:Enzyme Induction; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics / Q000378:metabolism; D010457:Peptidoglycan / Q000378:metabolism; D001618:beta-Lactamases / Q000096:biosynthesis*
C084284:AmpG protein, Bacteria; D001426:Bacterial Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010457:Peptidoglycan; C062460:AmpD protein, Bacteria; D009238:N-Acetylmuramoyl-L-alanine Amidase; D001618:beta-Lactamases