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.

Conference Title

The 10th International Palestinian Conference of Laboratory Medicine (IPCLM-10) and the 15th Arab Conference of Clinical Biology (ACCB-15)

Conference Country

Palestine

Conference Date

April 18, 2018 - April 22, 2018

Conference Sponsor

The Palestinian Medical Technology Association & The Arab Federation of Clinical Biology (AFCB)