The structure and proinflammatory activity of the lipopolysaccharide from Burkholderia multivorans and the differences between clonal strains colonizing pre and posttransplanted lungs

Abstract

The Burkholderia cepacia complex is a group of Gram-negative bacteria that are opportunistic pathogens for humans especially in cystic fibrosis patients. Lipopolysaccharide (LPS) molecules are potent virulence factors of Gram-negative bacteria organisms essential for bacterial survival. A complete analysis of the bacterial lipopolysaccharide structure to function relationship is required to understand the chemical basis of the inflammatory process. We have therefore investigated the structures of lipopolysaccharides from clonally identical Burkholderia multivorans strains (genomovar II) isolated pre- and post-lung transplantation through compositional analysis, mass spectrometry, and 2D NMR spectroscopy. We tested the LPS proinflammatory activity as a stimulant of human myelomonocytic U937 cell cytokine induction and assessed TLR4/MD2 signaling. Marked changes between the paired strains were found in the lipid A-inner core region. Such structural variations can contribute to the bacterial survival and persistence of infections despite the loss of a CF milieu following lung transplantation.

In Vitro Susceptibility of Burkholderia vietnamiensis to Aminoglycosides

“…Moreover, mutations in genes that code for proteins involved in the assembly of the O polysaccharide (44) and core oligosaccharide (34) portions of LPS can contribute to increased resistance to tobramycin and cationic peptides, respectively. BCC lipid A contains at least one Ara4N residue (10,(23)(24)(25), and furthermore, polymyxin and protegrin-1, a cationic peptide, bind poorly to whole BCC bacteria and to purified BCC LPS (1,38). Efflux systems that accommodate aminoglycosides have been identified in a number of organisms, including P. aeruginosa and Burkholderia pseudomallei (42).…”

Structural Elucidation of a Novel B. cenocepacia ET‐12 Lipooligosaccharide Isolated from a Cystic Fibrosis Patient after Lung Transplantation

“…[8] In contrast to the ET-12 strain already extensively characterised, the highly conserved residue of β-Glc present in the inner core is, in turn, glycosylated at O-6 by a terminal Gal residue, as reported for B. caryophylli and for B. multivorans. [11,17] In the ET-12 clone analysed herein, a short LPS core oligosaccharide portion was biosynthesised, in contrast to the core oligosaccharide from strain J2315 B. cenocepacia ET-12. [8] In the known B. cenocepacia core, there is a α--Gal residue connected to the C-3-and C-7-branched heptose residue, which is substituted by the trisaccharide α--Rha(1Ǟ3)-β--QuiNAc(1Ǟ7)-α-,-Hep(1Ǟ) at C-2.…”

“…Peaks at m/z = 1670.3 (P 1 ), 1800.8 (P 2 ) and 1932.0 (P 3 ) are consistent with a pentaacylated lipid A carrying two ester-linked 14:0 (3-OH) acyl chains with 0, 1 and 2 Ara4N residues, respectively. In analogy with other lipid A from Burkholderia, [6,11] we identified the position of the secondary fatty acid 14:0 chain on the GlcN II by MS analysis of the lipid A moiety after acetate buffer hydrolysis. Briefly, the positive-ion MALDI-MS (not shown) presents an in-source fragmentation due to the breakage of the glycosidic linkage between the two GlcN units, giving rise to a triacylated oxonium ion at m/z = 933.1, carrying one 14:0 (3-OH), one 14:0 and one 16:0 (3-OH) residue at the nonreducing GlcN unit.…”

Kdo hydroxylase is an inner core assembly enzyme in the Ko-containing lipopolysaccharide biosynthesis

“…While quantitative amounts of Ko [31,32] are found in BCC LPS, a Ko-derivatized lipid A moiety is observed as a minor component of LPS isolated from Y. pestis grown at 6–7 °C [33]. This difference might result from temperature dependent gene expression in Yersinia or the endogenous character of each KdoO (52% sequence identity and 64% sequence similarity between BaKdoO and YpKdoO) but it might also reflect the relative efficiency of WaaC and KdoO in each species, as these enzymes compete for common substrates.…”