Role of precursor translocation in coordination of murein and phospholipid synthesis in Escherichia coli.
Inhibition of phospholipid synthesis in Escherichia coli by either cerulenin treatment or glycerol starvation of a glycerol-auxotrophic mutant resulted in a concomitant block of murein synthesis. The intracellular pool of cytoplasmic and lipid-linked murein precursors was not affected by an inhibition of phospholipid synthesis, nor was the activity of the penicillin-binding proteins. In addition, a decrease in the activity of the two lipoprotein murein hydrolases, the lytic transglycosylases A and B, could not be demonstrated. The indirect inhibition of murein synthesis by cerulenin resulted in a 68% decrease of trimeric muropeptide structures, proposed to represent the attachment points of newly added murein. Importantly, inhibition of phospholipid synthesis also inhibited O-antigen synthesis with a sensitivity and kinetics similar to those of murein synthesis. It is concluded that the step common for murein and O-antigen synthesis, the translocation of the respective bactoprenolphosphate-linked precursor molecules, is affected by an inhibition of phospholipid synthesis. Consistent with this assumption, it was shown that murein synthesis no longer depends on ongoing phospholipid synthesis in ether-permeabilized cells. We propose that the assembly of a murein-synthesizing machinery, a multienzyme complex consisting of murein hydrolases and synthases, at specific sites of the membrane, where integral membrane proteins such as RodA and FtsW facilitate the translocation of the lipid-linked murein precursors to the periplasm, depends on ongoing phospholipid synthesis. This would explain the well-known phenomenon that both murein synthesis and antibiotic-induced autolysis depend on phospholipid synthesis and thereby indirectly on the stringent control.
Ehlert
K
K
Abteilung Biology, Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
Höltje
J V
JV
D000667:Ampicillin / Q000378:metabolism; D001426:Bacterial Proteins; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism; D002463:Cell Membrane Permeability; D002569:Cerulenin / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism*; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase / Q000378:metabolism; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000378:metabolism; D019081:O Antigens / Q000096:biosynthesis; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan / Q000096:biosynthesis* / Q000737:chemistry; D010458:Peptidyl Transferases; D010743:Phospholipids / Q000096:biosynthesis*; D011498:Protein Precursors / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D019081:O Antigens; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D010743:Phospholipids; D011498:Protein Precursors; D002569:Cerulenin; D000667:Ampicillin; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D009238:N-Acetylmuramoyl-L-alanine Amidase