Lipid A Biosynthesis in Rhizobium leguminosarum: Role of a 2-Keto-3-Deoxyoctulosonate-Activated 4' Phosphatase

Lipid A from several strains of the N2-fixing bacterium Rhizobium leguminosarum displays significant structural differences from Escherichia coli lipid A, one of which is the complete absence of phosphate groups. However, the first seven enzymes of E. coli lipid A biosynthesis, leading from UDP-GlcN...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1995-08, Vol.92 (16), p.7352-7356
Main Authors: Neil P. J. Price, Jeyaretnam, Ben, Carlson, Russell W., Kadrmas, Julie L., Christian R. H. Raetz, Brozek, Kathryn A.
Format: Article
Language:English
Subjects:
Bacteria
Bacteriology
Biochemistry
Biosynthesis
Carbohydrate Sequence
Chromatography
Endotoxins
Enzymes
Escherichia coli - metabolism
Genes, Bacterial
Lipid A - biosynthesis
Lipid A - chemistry
Lipids
Molecular Sequence Data
Molecular Structure
Mutation
Phosphatases
Phosphates
Phosphates - chemistry
Phosphoric Monoester Hydrolases - genetics
Phosphoric Monoester Hydrolases - metabolism
Rhizobium leguminosarum
Rhizobium leguminosarum - genetics
Rhizobium leguminosarum - metabolism
Silica gel
Sinorhizobium meliloti - metabolism
Species Specificity
Subcellular Fractions - metabolism
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Summary:Lipid A from several strains of the N2-fixing bacterium Rhizobium leguminosarum displays significant structural differences from Escherichia coli lipid A, one of which is the complete absence of phosphate groups. However, the first seven enzymes of E. coli lipid A biosynthesis, leading from UDP-GlcNAc to the phosphorylated intermediate, 2-ke-to-3-deoxyoctulosonate (Kdo2)-lipid IVA, are present in R. leguminosarum. We now describe a membrane-bound phosphatase in R. leguminosarum extracts that removes the 4' phosphate of Kdo2-lipid IVA. The 4' phosphatase is selective for substrates containing the Kdo domain. It is present in extracts of R. leguminosarum biovars phaseoli, viciae, and trifolii but is not detectable in E. coli and Rhizobium meliloti. A nodulation-defective strain (24AR) of R. leguminosarum biovar trifolii, known to contain a 4' phosphate residue on its lipid A, also lacks measurable 4' phosphatase activity. The Kdo-dependent 4' phosphatase appears to be a key reaction in a pathway for generating phosphate-deficient lipid A.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.92.16.7352