Undecaprenyl phosphate recycling comes out of age.
The recycling of the lipid carrier undecaprenyl-phosphate (Und-P) requires the dephosphorylation of Und-PP, a reaction proposed to occur at the external or periplasmic side of the bacterial cell membrane. In this issue of Molecular Microbiology, experiments based on the analysis of lipopolysaccharide modifications in Escherichia coli demonstrate that the phosphorylation of lipid A at position 1 is catalysed by the membrane enzyme LpxT (formerly YeiU). This enzyme specifically transfers the distal phosphate group from Und-PP to lipid A 1-phosphate to produce lipid A 1-diphosphate. Furthermore, this reaction requires a functionally intact MsbA protein, which catalyses the transfer of lipid A across the membrane, confirming that the LpxT-mediated lipid A modification occurs on the periplasmic side of the membrane. These observations provide a novel and unexpected link between periplasmic lipid A modifications and the Und-PP recycling pathway.
Valvano
Miguel A
MA
Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada N6A 5C1. mvalvano@uwo.ca
D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D008050:Lipid A / Q000378:metabolism*; D008954:Models, Biological; D010766:Phosphorylation; D011106:Polyisoprenyl Phosphates / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism
D008050:Lipid A; D011106:Polyisoprenyl Phosphates; D011134:Polysaccharides; C009621:undecaprenyl phosphate