Sensing Mg2+ contributes to the resistance of Pseudomonas aeruginosa to complement-mediated opsonophagocytosis

Mohammad Qadi, Sofía Izquierdo-Rabassa, Margalida Mateu Borrás, Antonio Doménech-Sánchez, Carlos Juan, Joanna B. Goldberg, Robert E.W. Hancock, Sebastián Albertí

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Pseudomonas aeruginosa adaptation to survive in the host hinges on its ability to probe the environment and respond appropriately. Rapid adaptation is often mediated by two-component regulatory systems, such as the PhoP/PhoQ system that responds to Mg2+ ion concentration. However, there is limited information about the role of PhoQ in P. aeruginosa bloodstream infections. We used a murine model of systemic infection to test the virulence of a PhoQ-deficient mutant. Mutation of PhoQ impaired the virulence and the ability to cause bacteremia of P. aeruginosa. In the presence of blood concentrations of Mg2+, a PhoQ mutant bound more C3 and was more susceptible to complement-mediated opsonophagocytosis than the parent strain, suggesting a direct effect of the Mg2+ on the modulation of expression of a bacterial component controlled by the PhoP/PhoQ system. Ligand blot analysis, C3 binding experiments and opsonophagocytosis assays identified this component as the outer membrane protein OprH, expression of which impaired the virulence of P. aeruginosa in a murine model of systemic infection. We demonstrate that expression of PhoQ is essential to detect Mg2+ and reduce the expression of OprH, a previously unrecognized C3 binding molecule that promotes the opsonophagocytosis of P. aeruginosa.

Original languageEnglish
Pages (from-to)4278-4286
Number of pages9
JournalEnvironmental Microbiology
Volume19
Issue number10
DOIs
Publication statusPublished or Issued - Oct 2017
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics

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