Biosynthesis of undecaprenyl phosphate-galactosamine and undecaprenyl phosphate-glucose in Francisella novicida.
Lipid A of Francisella tularensis subsp. novicida contains a galactosamine (GalN) residue linked to its 1-phosphate group. As shown in the preceding paper, this GalN unit is transferred to lipid A from the precursor undecaprenyl phosphate-beta-D-GalN. A small portion of the free lipid A of Francisella novicida is further modified with a glucose residue at position-6'. We now demonstrate that the two F. novicida homologues of Escherichia coli ArnC, designated FlmF1 and FlmF2, are essential for lipid A modification with glucose and GalN, respectively. Recombinant FlmF1 expressed in E. coli selectively condenses undecaprenyl phosphate and UDP-glucose in vitro to form undecaprenyl phosphate-glucose. Recombinant FlmF2 selectively catalyzes the condensation of undecaprenyl phosphate and UDP-N-acetylgalactosamine to generate undecaprenyl phosphate-N-acetylgalactosamine. On the basis of an analysis of the lipid A composition of flmF1 and flmF2 mutants of F. novicida, we conclude that FlmF1 generates the donor substrate for the modification of F. novicida free lipid A with glucose, whereas FlmF2 generates the immediate precursor of the GalN donor substrate, undecaprenyl phosphate-beta-D-GalN. A novel deacetylase, present in membranes of F. novicida, removes the acetyl group from undecaprenyl phosphate-N-acetylgalactosamine to yield undecaprenyl phosphate-beta-D-GalN. This deacetylase may have an analogous function to the deformylase that generates undecaprenyl phosphate-4-amino-4-deoxy-alpha-l-arabinose from undecaprenyl phosphate-4-deoxy-4-formylamino-alpha-l-arabinose in polymyxin-resistant strains of E. coli and Salmonella typhimurium.
Song
Feng
F
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
Guan
Ziqiang
Z
Raetz
Christian R H
CR
D000116:Acetylgalactosamine / Q000096:biosynthesis* / Q000737:chemistry; D000123:Acetyltransferases / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D002853:Chromatography, Liquid; D004926:Escherichia coli / Q000378:metabolism; D005603:Francisella / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D005688:Galactosamine / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry; D005960:Glucosides / Q000096:biosynthesis* / Q000737:chemistry; D008050:Lipid A / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D005810:Multigene Family; D009154:Mutation / Q000235:genetics; D011106:Polyisoprenyl Phosphates / Q000096:biosynthesis* / Q000737:chemistry; D011994:Recombinant Proteins / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
D001426:Bacterial Proteins; D005960:Glucosides; D008050:Lipid A; D011106:Polyisoprenyl Phosphates; D011994:Recombinant Proteins; C542101:undecaprenyl phosphate-galactosamine; C542102:undecaprenyl phosphate-glucose; C009621:undecaprenyl phosphate; D005688:Galactosamine; D000123:Acetyltransferases; D000116:Acetylgalactosamine