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

• Published in: International journal of molecular sciences Vol. 24; no. 24; p. 17313
• Main Authors: Pérez-Ortega, Jesús, van Boxtel, Ria, Plisnier, Michel, Ingels, Dominique, Devos, Nathalie, Sijmons, Steven, Tommassen, Jan
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09.12.2023
• Subjects: 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo); Bacteria; Bordetella pertussis; Cell division; E coli; endotoxin; Enzymes; Fatty acids; Genetic engineering; Gram-negative bacteria; Kdo kinase; Kdo transferase; Kinases; Lipids; Phosphatase; Phosphates; Vaccines; Whooping cough; lipid A phosphatase; Kdo kinase; Toll-like receptor 4; cell division; phosphoethanolamine transferase; Bordetella pertussis; lipopolysaccharide; Kdo transferase; 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo); endotoxin
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms242417313

Previously developed whole-cell vaccines against , 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 through the heterologous production of the phosphatase LpxE from 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 . The and genes, responsible for the incorporation of a single 3-deoxy-D- -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 . 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 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.