title: Structural derivation of lipid A from Cronobacter sakazakii using tandem mass spectrometry.
abstract: BACKGROUND
  Cronobacter sakazakii is a Gram-negative opportunistic pathogen that can cause necrotizing enterocolitis, bacteremia, and meningitis. Lipid A, the glycolipid membrane anchor of lipopolysaccharide (LPS), is a potential virulence factor for C. sakazakii. Given the potential importance of this molecule in infection and virulence, structural characterization of lipid A was carried out.
  
  
  METHODS
  The structural characterization of lipid A extracted from C. sakazakii was performed using electrospray ionization and collision-induced dissociation in a linear ion trap mass spectrometer. Specifically, for detailed structural characterization, hierarchical tandem mass spectrometry was performed on the dominant ions present in the precursor ion mass spectra. By comparing the C. sakazakii fragmentation pathways to those of the known structure of E. coli lipid A, a structure of C. sakazakii lipid A was derived.
  
  
  RESULTS
  The precursor ion at m/z 1796 from C. sakazakii is produced from a lipid A molecule where the acyl chains between the 2'b (C14) and 3'b (C12) positions are reversed as compared to E. coli lipid A. Additionally, the precursor ion at m/z 1824 from C. sakazakii corresponds to an E. coli structure with the same acyl chain at the 2'b position (C14), but a longer acyl chain (C14) at the 3'b position versus m/z 1796.
  
  
  CONCLUSIONS
  Two lipid A structures were derived for the C. sakazakii ions at m/z 1796 and 1824. They differed in composition at the 2'b and 3'b acyl chain substituents, which may be a result of differences in substrate specificity of the two lipid A acyl chain transferases: LpxL and LpxM. Copyright © 2016 John Wiley & Sons, Ltd.
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China. yanyanli1123@hotmail.com.|Joint International Research Laboratory of Food Safety, Jiangnan University, Wuxi, 214122, China. yanyanli1123@hotmail.com.
authors: Yanyan
authors: Y
authors: Li
authors: Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA.
authors: Sung Hwan
authors: SH
authors: Yoon
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.|Joint International Research Laboratory of Food Safety, Jiangnan University, Wuxi, 214122, China.
authors: Xiaoyuan
authors: X
authors: Wang
authors: Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA.
authors: Robert K
authors: RK
authors: Ernst
authors: Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, Baltimore, MD, 21201, USA. dgoodlett@rx.umaryland.edu.
authors: David R
authors: DR
authors: Goodlett
mesh_terms: D044083:Cronobacter sakazakii / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism; D008050:Lipid A / Q000737:chemistry* / Q000378:metabolism; D015394:Molecular Structure; D053719:Tandem Mass Spectrometry
chemical_list: D008050:Lipid A