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Rapid Commun Mass Spectrom. 2016 Oct 30;30(20):2265-70. doi: 10.1002/rcm.7712.

Structural derivation of lipid A from Cronobacter sakazakii using tandem mass spectrometry.

Author information

1
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China. yanyanli1123@hotmail.com.
2
Joint International Research Laboratory of Food Safety, Jiangnan University, Wuxi, 214122, China. yanyanli1123@hotmail.com.
3
Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA.
4
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
5
Joint International Research Laboratory of Food Safety, Jiangnan University, Wuxi, 214122, China.
6
Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, Baltimore, MD, 21201, USA. dgoodlett@rx.umaryland.edu.

Abstract

RATIONALE:

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.

PMID:
27502448
DOI:
10.1002/rcm.7712
[Indexed for MEDLINE]

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