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

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10 Citations (Scopus)


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
Issue number10
Publication statusPublished or Issued - Oct 2017
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics

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