title: UVliPiD: A UVPD-Based Hierarchical Approach for De Novo Characterization of Lipid A Structures.
abstract: The lipid A domain of the endotoxic lipopolysaccharide layer of Gram-negative bacteria is comprised of a diglucosamine backbone to which a variable number of variable length fatty acyl chains are anchored. Traditional characterization of these tails and their linkages by nuclear magnetic resonance (NMR) or mass spectrometry is time-consuming and necessitates databases of pre-existing structures for structural assignment. Here, we introduce an automated de novo approach for characterization of lipid A structures that is completely database-independent. A hierarchical decision-tree MS(n) method is used in conjunction with a hybrid activation technique, UVPDCID, to acquire characteristic fragmentation patterns of lipid A variants from a number of Gram-negative bacteria. Structural assignments are derived from integration of key features from three to five spectra and automated interpretation is achieved in minutes without the need for pre-existing information or candidate structures. The utility of this strategy is demonstrated for a mixture of lipid A structures from an enzymatically modified E. coli lipid A variant. A total of 27 lipid A structures were discovered, many of which were isomeric, showcasing the need for a rapid de novo approach to lipid A characterization.
authors.affiliation: Department of Chemistry, University of Texas , Austin, Texas 78712, United States.
authors.forename: Lindsay J
authors.initials: LJ
authors.lastname: Morrison
authors.affiliation: Department of Chemistry, University of Texas , Austin, Texas 78712, United States.
authors.forename: W Ryan
authors.initials: WR
authors.lastname: Parker
authors.affiliation: Department of Chemistry, University of Texas , Austin, Texas 78712, United States.
authors.forename: Dustin D
authors.initials: DD
authors.lastname: Holden
authors.affiliation: Department of Infectious Diseases, University of Georgia , Athens, Georgia 30602, United States.
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Henderson
authors.affiliation: Department of Molecular Biosciences, University of Texas , Austin, Texas 78712, United States.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Boll
authors.affiliation: Department of Infectious Diseases, University of Georgia , Athens, Georgia 30602, United States.
authors.forename: M Stephen
authors.initials: MS
authors.lastname: Trent
authors.affiliation: Department of Chemistry, University of Texas , Austin, Texas 78712, United States.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brodbelt
mesh_terms: D004926:Escherichia coli / Q000737:chemistry; D008050:Lipid A / Q000737:chemistry*; D013058:Mass Spectrometry; D011487:Protein Conformation; D014466:Ultraviolet Rays
chemical_list: D008050:Lipid A