Minor Modifications to the Phosphate Groups and the C3′ Acyl Chain Length of Lipid A in Two Bordetella pertussis Strains, BP338 and 18-323, Independently Affect Toll-like Receptor 4 Protein Activation

Abstract

Background: Lipid A activation of TLR4 shapes immunity to Gram-negative bacteria. Results: In Bordetella pertussis lipid A, the genetic basis for longer C3Ј acyl chains and glucosamine modification of the phosphate groups was identified; each variation independently increased TLR4 activation. Conclusion: Minor changes in the penta-acylated B. pertussis lipid A affect TLR4 activation. Significance: This aids our understanding how lipid A species interact with TLR4.

Bordetella pertussis Naturally Occurring Isolates with Altered Lipooligosaccharide Structure Fail To Fully Mature Human Dendritic Cells

“…Using mass spectrometry, we showed that this lipid A alteration described for the B1121/18-323 strain also occurs in the clinical B. pertussis isolates B1120 and B0442. Furthermore, a mutation in the lpxLA gene, leading to an S173ϾL substitution, as also described recently for B. pertussis 18-323 by Shah et al (31), was observed in these two strains. This substitution likely explains the presence of C 10 -OH or C 12 -OH acyl chains instead of C 14 -OH at the C-3= position of the lipid A molecule.…”

“…Besides the alteration in the length of the acyl chain on the C-3= position, a lack of GlcN modification was also found with all three isolates. Surprisingly, for the isolates B0442 and B1120, no mutations were found in the genes involved in GlcN modification, unlike a deletion mutation in the lgmB gene described for the B1121/18-323 strain (31). In the Bvg ϩ or virulent phase of the bacterium, the genes involved in the GlcN modifications are transcribed, leading to the addition of GlcN to the lipid A moieties (63).…”

“…To determine whether the structural changes found in the LOS of the B0442, B1120, and B1121 isolates correspond to alterations in the genes involved in LOS synthesis (45), the sequences of these genes were analyzed and compared to the gene sequence of the Tohama I strain (Table 2). Shah et al described for the B1121/18-323 strain a substitution of a leucine for a serine at amino acid 173 (S173ϾL) in the LpxA protein (31). This is the first enzyme of the LPS biosynthesis pathway, and it catalyzes acylation of the C-3 position of the UDP N-acetylglucosamine backbone, forming UDP-3-O-acyl N-acetylglucosamine (46).…”

Enzymatic Modification of Lipid A by ArnT Protects Bordetella bronchiseptica against Cationic Peptides and Is Required for Transmission

“…The modification of phosphate groups with aminoarabinose decreases the net negative charge on LPS and renders S. Typhimurium resistant to the antimicrobial cationic peptide, polymyxin (15). In B. pertussis, the ArnT activity of the homologue LgmB is induced in the Bvg ϩ phase and mediates the addition of GlcN to both terminal phosphate groups of the lipid A, which is associated with increased stimulation of TLR4 activity in an HEK-Blue assay and upon infection of human macrophages (10,11,16 3OH-C14 3OH-C14 3OH-C14 3OH-C14 3OH-C14 3OH-C14 C14 3OH-C14 C16 C12 C14 C12 C12 C14 3OH-C14 3OH- killing by polymyxin B (10). ArnT-mediated addition of GlcN has also been reported for B. parapertussis (17) and B. bronchiseptica strain 4650 (11).…”

Structural and biological characteristics of different forms of V. filiformis lipid A: use of MS to highlight structural discrepancies

“…One of the best illustrated examples of structure to activity relationships, related to the low number and short length of FA carbon chains, is that of B. pertussis, displaying mixtures of tetra-and penta-acyl molecular lipid A species. This example has been extensively studied (20,39,45) and compared with standard LPS as well as to closely related structures differing by only two carbons in a single FA at C3′ or the presence of GlcN on both phosphate groups. Both B. pertussis lipids A were hypo-acylated with tetra-and penta-acyl molecular species.…”