Membrane intermediates in the peptidoglycan metabolism of Escherichia coli: possible roles of PBP 1b and PBP 3.
The two membrane precursors (pentapeptide lipids I and II) of peptidoglycan are present in Escherichia coli at cell copy numbers no higher than 700 and 2,000 respectively. Conditions were determined for an optimal accumulation of pentapeptide lipid II from UDP-MurNAc-pentapeptide in a cell-free system and for its isolation and purification. When UDP-MurNAc-tripeptide was used in the accumulation reaction, tripeptide lipid II was formed, and it was isolated and purified. Both lipids II were compared as substrates in the in vitro polymerization by transglycosylation assayed with PBP 1b or PBP 3. With PBP 1b, tripeptide lipid II was used as efficiently as pentapeptide lipid II. It should be stressed that the in vitro PBP 1b activity accounts for at best to 2 to 3% of the in vivo synthesis. With PBP 3, no polymerization was observed with either substrate. Furthermore, tripeptide lipid II was detected in D-cycloserine-treated cells, and its possible in vivo use in peptidoglycan formation is discussed. In particular, it is speculated that the transglycosylase activity of PBP 1b could be coupled with the transpeptidase activity of PBP 3, using mainly tripeptide lipid II as precursor.
van Heijenoort
Y
Y
Centre National de la Recherche Scientifique, Université Paris-Sud, Orsay, France.
Gómez
M
M
Derrien
M
M
Ayala
J
J
van Heijenoort
J
J
D001426:Bacterial Proteins; D002352:Carrier Proteins; D002462:Cell Membrane / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D006031:Glycosylation; D006602:Hexosyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000302:isolation & purification / Q000378:metabolism*; D002267:Muramoylpentapeptide Carboxypeptidase; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan / Q000096:biosynthesis*; D010458:Peptidyl Transferases / Q000302:isolation & purification / Q000378:metabolism*; D011103:Polyisoprenyl Phosphate Monosaccharides / Q000378:metabolism; D011104:Polyisoprenyl Phosphate Oligosaccharides / Q000302:isolation & purification / Q000378:metabolism; D014538:Uridine Diphosphate N-Acetylmuramic Acid / Q000031:analogs & derivatives / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004151:Dipeptides; D009097:Multienzyme Complexes; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D011103:Polyisoprenyl Phosphate Monosaccharides; D011104:Polyisoprenyl Phosphate Oligosaccharides; D014538:Uridine Diphosphate N-Acetylmuramic Acid; C074776:N-acetylglucosaminyl-N-acetylmuramyl(tripeptide)-pyrophosphate-undecaprenol; C002225:UDP-N-acetylmuramic acid pentapeptide; C002956:alanylalanine; C062770:undecaprenyl diphosphate-(N-acetylglucosaminyl)(1-4)-N-acetylmuramoyl pentapeptide; C062771:undecaprenyl biphosphate-N-acetylmuramoyl-pentapeptide; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase