Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Escherichia coli [ICD11:
XN6P4 
]
The structure was elucidated in this paperNCBI PubMed ID: 20795687Journal NLM ID: 0370623Publisher: American Chemical Society
Correspondence: raetz
biochem.duke.edu
Institutions: Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
The lipid A moiety of Escherichia coli lipopolysaccharide is a hexaacylated disaccharide of glucosamine that is phosphorylated at the 1 and 4' positions. Expression of the Francisella novicida lipid A 1-phosphatase FnLpxE in E. coli results in dephosphorylation of the lipid A proximal unit. Coexpression of FnLpxE and the Rhizobium leguminosarum lipid A oxidase RlLpxQ in E. coli converts much of the proximal glucosamine to 2-amino-2-deoxygluconate. Expression of the F. novicida lipid A 4'-phosphatase FnLpxF in wild-type E. coli has no effect because FnLpxF cannot dephosphorylate hexaacylated lipid A. However, expression of FnLpxF in E. coli lpxM mutants, which synthesize pentaacylated lipid A lacking the secondary 3'-myristate chain, causes extensive 4'-dephosphorylation. Coexpression of FnLpxE and FnLpxF in lpxM mutants results in massive accumulation of lipid A species lacking both phosphate groups, and introduction of RlLpxQ generates phosphate-free lipid A variants containing 2-amino-2-deoxygluconate. The proposed lipid A structures were confirmed by electrospray ionization mass spectrometry. Strains with 4'-dephosphorylated lipid A display increased polymyxin resistance. Heptose-deficient mutants of E. coli lacking both the 1- and 4'-phosphate moieties are viable on plates but sensitive to CaCl(2). Our methods for reengineering lipid A structure may be useful for generating novel vaccines and adjuvants.
lipopolysaccharides, Escherichia coli, Rhizobia, mass spectrometry, lipid A structure, polymyxin
Structure type: oligomer ; 972.57 [M-2H]2-
Location inside paper: p.8327, fig.2, product III, p.8333, fig.6B
Compound class: lipid A
Contained glycoepitopes: IEDB_130650,IEDB_130659,IEDB_141807,IEDB_151531,IEDB_534864
Methods: DNA techniques, ESI-MS, mild acid hydrolysis, genetic methods, enzymatic modification
Enzymes that release or process the structure: LpxE
Comments, role: lipid A of mutant strain E. coli SR8209/pWSK29-LpxE LPS
Related record ID(s): 31140, 31185, 31186, 31187, 31188, 31189, 31190, 31192, 31193, 31194, 31195, 31196
NCBI Taxonomy refs (TaxIDs): 562
Show glycosyltransferases
There is only one chemically distinct structure:
Found 
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