Periplasmic phosphorylation of lipid A is linked to the synthesis of undecaprenyl phosphate.
One-third of the lipid A found in the Escherichia coli outer membrane contains an unsubstituted diphosphate unit at position 1 (lipid A 1-diphosphate). We now report an inner membrane enzyme, LpxT (YeiU), which specifically transfers a phosphate group to lipid A, forming the 1-diphosphate species. (32)P-labelled lipid A obtained from lpxT mutants do not produce lipid A 1-diphosphate. In vitro assays with Kdo(2)-[4'-(32)P]lipid A as the acceptor shows that LpxT uses undecaprenyl pyrophosphate as the substrate donor. Inhibition of lipid A 1-diphosphate formation in wild-type bacteria was demonstrated by sequestering undecaprenyl pyrophosphate with the cyclic polypeptide antibiotic bacitracin, providing evidence that undecaprenyl pyrophosphate serves as the donor substrate within whole bacteria. LpxT-catalysed phosphorylation is dependent upon transport of lipid A across the inner membrane by MsbA, a lipid A flippase, indicating a periplasmic active site. In conclusion, we demonstrate a novel pathway in the periplasmic modification of lipid A that is directly linked to the synthesis of undecaprenyl phosphate, an essential carrier lipid required for the synthesis of various bacterial polymers, such as peptidoglycan.
Laboratoire des Enveloppes Bactériennes et Antibiotiques, Unité Mixte de Recherche 8619 CNRS, Université Paris-Sud, 91405 Orsay, France.
Thierry
T
Touzé
An X
AX
Tran
Jessica V
JV
Hankins
Dominique
D
Mengin-Lecreulx
M Stephen
MS
Trent
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001414:Bacitracin / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism; D048168:Escherichia coli K12 / Q000201:enzymology / Q000235:genetics; D008050:Lipid A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism; D009154:Mutation; D010458:Peptidyl Transferases / Q000378:metabolism; D019897:Periplasm / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011106:Polyisoprenyl Phosphates / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008050:Lipid A; D008563:Membrane Lipids; C079726:MsbA protein, Bacteria; D010710:Phosphates; D011106:Polyisoprenyl Phosphates; D001414:Bacitracin; C009621:undecaprenyl phosphate; D010458:Peptidyl Transferases; D011755:Pyrophosphatases; C503879:undecaprenyl pyrophosphate phosphatase