Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Salmonella enterica [ICD11:
XN5VC 
];
infection due to Escherichia coli [ICD11:
XN6P4 ]
The structure was elucidated in this paperNCBI PubMed ID: 11535605Publication DOI: 10.1074/jbc.M106962200Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: raetz
biochem.duke.edu
Institutions: Department of Biochemistry and the Duke NMR Spectroscopy Center and Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, Middle Atlantic Mass Spectrometry Laboratory, Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185, USA
Polymyxin-resistant mutants of Escherichia coli and Salmonella typhimurium accumulate a novel minor lipid that can donate 4-amino-4-deoxy-l-arabinose units (l-Ara4N) to lipid A. We now report the purification of this lipid from a pss(-) pmrA(C) mutant of E. coli and assign its structure as undecaprenyl phosphate-α-L-Ara4N. Approximately 0.2 mg of homogeneous material was isolated from an 8-liter culture by solvent extraction, followed by chromatography on DEAE-cellulose, C18 reverse phase resin, and silicic acid. Matrix-assisted laser desorption ionization/time of flight mass spectrometry in the negative mode yielded a single species [M - H](-) at m/z 977.5, consistent with undecaprenyl phosphate-α-L-Ara4N (M(r) = 978.41). (31)P NMR spectroscopy showed a single phosphorus atom at -0.44 ppm characteristic of a phosphodiester linkage. Selective inverse decoupling difference spectroscopy demonstrated that the undecaprenyl phosphate group is attached to the anomeric carbon of the l-Ara4N unit. One- and two-dimensional (1)H NMR studies confirmed the presence of a polyisoprene chain and a sugar moiety with chemical shifts and coupling constants expected for an equatorially substituted arabinopyranoside. Heteronuclear multiple-quantum coherence spectroscopy analysis demonstrated that a nitrogen atom is attached to C-4 of the sugar residue. The purified donor supports in vitro conversion of lipid IV(A) to lipid II(A), which is substituted with a single l-Ara4N moiety. The identification of undecaprenyl phosphate-α-L-Ara4N implies that l-Ara4N transfer to lipid A occurs in the periplasm of polymyxin-resistant strains, and establishes a new enzymatic pathway by which Gram-negative bacteria acquire antibiotic resistance.
Escherichia coli, lipid A, polymyxin-resistant mutants, Salmonella typhimurium
Structure type: structural motif or average structure
Location inside paper: p.43134, fig.1
Compound class: lipid A
Contained glycoepitopes: IEDB_135394,IEDB_135515,IEDB_141807,IEDB_151531,IEDB_176772,IEDB_534864
Methods: 13C NMR, 1H NMR, NMR-2D, DNA techniques, TLC, 31P NMR, MALDI-TOF MS, radiolabeling, NMR-1D, genetic methods, biochemical methods, radioactivity measurement
Biological activity: biochemical data
Enzymes that release or process the structure: ArnT
Comments, role: proposed structure
Related record ID(s): 5231
NCBI Taxonomy refs (TaxIDs): 90371,
562
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There is only one chemically distinct structure:
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(later renamed to: Salmonella enterica ssp. enterica sv. Typhimurium)