Biosynthesis of the Inner Core of Bordetella pertussis Lipopolysaccharides: Effect of Mutations on LPS Structure, Cell Division, and Toll-like Receptor 4 Activation

Jesús Pérez-Ortega, Ria Van boxtel, Michel Plisnier, Dominique Ingels, Nathalie Devos, Steven Sijmons, Jan Tommassen

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Previously developed whole-cell vaccines against Bordetella pertussis, the causative agent of whooping cough, appeared to be too reactogenic due to their endotoxin content. Reduction in endotoxicity can generally be achieved through structural modifications in the lipid A moiety of lipopolysaccharides (LPS). In this study, we found that dephosphorylation of lipid A in B. pertussis through the heterologous production of the phosphatase LpxE from Francisella novicida did, unexpectedly, not affect Toll-like receptor 4 (TLR4)-stimulating activity. We then focused on the inner core of LPS, whose synthesis has so far not been studied in B. pertussis. The kdtA and kdkA genes, responsible for the incorporation of a single 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) residue in the inner core and its phosphorylation, respectively, appeared to be essential. However, the Kdo-bound phosphate could be replaced by a second Kdo after the heterologous production of Escherichia coli kdtA. This structural change in the inner core affected outer-core and lipid A structures and also bacterial physiology, as reflected in cell filamentation and a switch in virulence phase. Furthermore, the eptB gene responsible for the non-stoichiometric substitution of Kdo-bound phosphate with phosphoethanolamine was identified and inactivated. Interestingly, the constructed inner-core modifications affected TLR4-stimulating activity. Whereas endotoxicity studies generally focus on the lipid A moiety, our data demonstrate that structural changes in the inner core can also affect TLR4-stimulating activity.
Original languageEnglish
Article number17313
Pages (from-to)1-23
Number of pages23
JournalInternational Journal of Molecular Sciences
Volume24
Issue number24
DOIs
Publication statusPublished - 5 Dec 2023

Keywords

  • Bordetella pertussis
  • cell division
  • 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo)
  • endotoxin
  • Kdo kinase
  • Kdo transferase
  • lipid A phosphatase
  • lipopolysaccharide
  • phosphoethanolaminetransferase
  • Toll-like receptor 4

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