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Periplasmic phosphorylation of lipid A is linked to the synthesis of undecaprenyl phosphate
Author(s) -
Touzé Thierry,
Tran An X.,
Hankins Jessica V.,
MenginLecreulx Dominique,
Trent M. Stephen
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.06044.x
Subject(s) - biology , periplasmic space , phosphorylation , phosphate , biochemistry , microbiology and biotechnology , gene , escherichia coli
Summary 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.