Study on the CID Fragmentation Pathways of Deprotonated 4’-Monophosphoryl Lipid A

Lipid A, the membrane-bound phosphoglycolipid component of bacteria, is held responsible for the clinical syndrome of gram-negative sepsis. In this study, the fragmentation behavior of a set of synthetic lipid A derivatives was studied by electrospray ionization multistage mass spectrometry (ESI-MSn), in conjunction with tandem mass spectrometry (MS/MS), using low-energy collision-induced dissociation (CID). Genealogical insight about the fragmentation pathways of the deprotonated 4’-monophosphoryl lipid A structural analogs led to proposals of a number of alternative dissociation routes that have not been reported previously. Each of the fragment ions was interpreted using various possible mechanisms, consistent with the principles of reactions described in organic chemistry. Specifically, the hypothesized mechanisms are: (i) cleavage of the C-3 primary fatty acid leaves behind an epoxide group attached to the reducing sugar; (ii) cleavage of the C-3’ primary fatty acid (as an acid) generates a cyclic phosphate connected to the nonreducing sugar; (iii) cleavage of the C-2’ secondary fatty acid occurs both in acid and ketene forms; iv) the C-2 and C-2’ primary fatty acids are eliminated as an amide and ketene, respectively; (v) the 0,2A2 cross-ring fragment contains a four-membered ring (oxetanose); (vi) the 0,4A2 ion is consecutively formed from the 0,2A2 ion by retro-aldol, retro-cycloaddition, and transesterification; and (vii) formations of H2PO4− and PO3− are associated with the formation of sugar epoxide. An understanding of the relation between 0,2A2 and 0,4A2-type sugar fragments and the different cleavage mechanisms of the two ester-linked primary fatty acids is invaluable for distinguishing lipid A isomers with different locations of a single ester-linked fatty acid (i.e., at C-3 or C-3’). Thus, in addition to a better comprehension of lipid A fragmentation processes in mass spectrometers, our observations can be applied for a more precise elucidation of naturally occurring lipid A structures.

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Chemical Structure of Lipid A Isolated fromFlavobacterium meningosepticum Lipopolysaccharide

Journal of Bacteriology ◽

10.1128/jb.180.15.3891-3899.1998 ◽

1998 ◽

Vol 180 (15) ◽

pp. 3891-3899 ◽

Cited By ~ 12

Author(s):

Hitomi Kato ◽

Yuji Haishima ◽

Takatoshi Iida ◽

Akira Tanaka ◽

Ken-ichi Tanamoto

Keyword(s):

Mass Spectrometry ◽

Fatty Acid ◽

Chemical Structure ◽

Lipid A ◽

Secondary Ion Mass Spectrometry ◽

Fatty Acid Distribution ◽

Fatty Acid Analysis ◽

Molar Ratio ◽

Hydroxyl Groups ◽

Monophosphoryl Lipid A

ABSTRACT The chemical structure of the lipid A of the lipopolysaccharide component isolated from Flavobacterium meningosepticum IFO 12535 was elucidated. Methylation and nuclear magnetic resonance analyses showed that two kinds of hydrophilic backbone exist in the free lipid A: a β (1→6)-linked 2-amino-2-deoxy-d-glucose, which is usually present in enterobacterial lipid A’s, and a 2-amino-6-O-(2,3-diamino-2,3-dideoxy-β-d-glucopyranosyl)-2-deoxy-d-glucose, in a molar ratio of 1.00:0.35. Both backbones were α-glycosidically phosphorylated in position 1, and the hydroxyl groups at positions 4, 4′, and 6′ were unsubstituted. Liquid secondary ion-mass spectrometry revealed a pseudomolecular ion atm/z 1673 [M-H]− as a major monophosphoryl lipid A component carrying five acyl groups. Fatty acid analysis showed that the lipid A contained 1 mol each of amide-linked (R)-3-OH iC17:0, ester-linked (R)-3-OH iC15:0, amide-linked (R)-3-O-(iC15:0)-iC17:0, and both amide- and ester-linked (R)-3-OH C16:0. Fatty acid distribution analyses using several mass spectrometry determinations demonstrated that the former two constituents were distributed on positions 2 and 3 of the reducing terminal unit of the backbones and that the latter two were attached to the 2′ and 3′ positions in the nonreducing terminal residue.

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Faculty Opinions recommendation of The vaccine adjuvant monophosphoryl lipid A as a TRIF-biased agonist of TLR4.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1087287.540302 ◽

2007 ◽

Author(s):

Rino Rappuoli

Keyword(s):

Lipid A ◽

Vaccine Adjuvant ◽

Monophosphoryl Lipid A ◽

Monophosphoryl Lipid ◽

Biased Agonist

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Monophosphoryl lipid A: an effective adjuvant for potentiating mucosal immune responses

Journal of Endotoxin Research ◽

10.1177/09680519990050030305 ◽

1999 ◽

Vol 5 (3) ◽

pp. 181-182 ◽

Cited By ~ 3

Author(s):

Suzanne M. Michalek ◽

Noel K. Childers ◽

Terry Greenway ◽

George Hajishengallis ◽

J. Terry Ulrich

Keyword(s):

Immune Responses ◽

Lipid A ◽

Monophosphoryl Lipid A ◽

Monophosphoryl Lipid ◽

Mucosal Immune Responses

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Monophosphoryl lipid A induces protection against LPS in medullary thick ascending limb through a TLR4-TRIF-PI3K signaling pathway

AJP Renal Physiology ◽

10.1152/ajprenal.00064.2017 ◽

2017 ◽

Vol 313 (1) ◽

pp. F103-F115 ◽

Cited By ~ 10

Author(s):

Bruns A. Watts ◽

Thampi George ◽

Edward R. Sherwood ◽

David W. Good

Keyword(s):

Bacterial Infections ◽

Lipid A ◽

Thick Ascending Limb ◽

Akt Inhibitor ◽

Erk Activation ◽

Akt Phosphorylation ◽

Medullary Thick Ascending Limb ◽

Monophosphoryl Lipid A ◽

Monophosphoryl Lipid

Monophosphoryl lipid A (MPLA) is a detoxified derivative of LPS that induces tolerance to LPS and augments host resistance to bacterial infections. Previously, we demonstrated that LPS inhibits [Formula: see text] absorption in the medullary thick ascending limb (MTAL) through a basolateral Toll-like receptor 4 (TLR4)-myeloid differentiation factor 88 (MyD88)-ERK pathway. Here we examined whether pretreatment with MPLA would attenuate LPS inhibition. MTALs from rats were perfused in vitro with MPLA (1 µg/ml) in bath and lumen or bath alone for 2 h, and then LPS was added to (and MPLA removed from) the bath solution. Pretreatment with MPLA eliminated LPS-induced inhibition of [Formula: see text] absorption. In MTALs pretreated with MPLA plus a phosphatidylinositol 3-kinase (PI3K) or Akt inhibitor, LPS decreased [Formula: see text] absorption. MPLA increased Akt phosphorylation in dissected MTALs. The Akt activation was eliminated by a PI3K inhibitor and in MTALs from TLR4−/−or Toll/IL-1 receptor domain-containing adaptor-inducing IFN-β (TRIF)−/−mice. The effect of MPLA to prevent LPS inhibition of [Formula: see text] absorption also was TRIF dependent. Pretreatment with MPLA prevented LPS-induced ERK activation; this effect was dependent on PI3K. MPLA alone had no effect on [Formula: see text] absorption, and MPLA pretreatment did not prevent ERK-mediated inhibition of [Formula: see text] absorption by aldosterone, consistent with MPLA's low toxicity profile. These results demonstrate that pretreatment with MPLA prevents the effect of LPS to inhibit [Formula: see text] absorption in the MTAL. This protective effect is mediated directly through MPLA stimulation of a TLR4-TRIF-PI3K-Akt pathway that prevents LPS-induced ERK activation. These studies identify detoxified TLR4-based immunomodulators as novel potential therapeutic agents to prevent or treat renal tubule dysfunction in response to bacterial infections.

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Fatty Acids Produced by Neofusicoccum vitifusiforme and N. parvum, Fungi Associated with Grapevine Botryosphaeria Dieback

Agriculture ◽

10.3390/agriculture8120189 ◽

2018 ◽

Vol 8 (12) ◽

pp. 189 ◽

Cited By ~ 7

Author(s):

Maria Salvatore ◽

Selene Giambra ◽

Daniele Naviglio ◽

Marina DellaGreca ◽

Francesco Salvatore ◽

...

Keyword(s):

Mass Spectrometry ◽

Fatty Acids ◽

Gas Chromatography ◽

Fatty Acid ◽

Linoleic Acid ◽

Gas Chromatography Mass Spectrometry ◽

Fungal Pathogenicity ◽

Botryosphaeria Dieback ◽

Plant Pathogen Interaction ◽

Abundant Fatty Acid

There is evidence that secondary metabolites are involved in the fungal pathogenicity and virulence of Neofusicoccum spp. Fatty acids may also influence the plant–pathogen interaction but, so far, no information is available on their production by species of Neofusicoccum associated with Botryosphaeria dieback, which is a well-known syndrome of several plants with a complex etiology. In the present paper, the production of fatty acids in liquid medium, by strains of N. vitifusiforme and N. parvum associated with declining Sicilian vine plants, was evaluated. Data, acquired via gas chromatography–mass spectrometry (GC/MS), show the presence of linoleic acid as the most abundant fatty acid produced by both examined strains. In addition, the pathogenicity of N. vitifusiforme was tested on 2-year-old grapevine plants of cv. Inzolia.

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