Pseudopaline trafficking in Pseudomonas aeruginosa – PseudoTraffic

Metallophores are molecules with a high affinity for metals, synthesized, secreted and recovered by bacteria in order to ensure constant availability of metals, especially in most hostile environments such as the one encountered during bacterial infection of a host. In this context, we have recently discovered a new zincophore called pseudopaline, which is essential for the growth of Pseudomonas aeruginosa under infection conditions.
The "PseudoTraffic" project aims to decipher four enigmatic chronological steps that ensure efficient circulation of pseudopaline through bacterial envelopes. Each of the four project tasks will cover an unresolved aspect of the transport of pseudopaline through these bacterial envelopes. The first task of the project will consist in investigating the existence of a pseudopalome, which would ensure the coupling of pseudopaline biosynthesis with the export steps in order to optimize secretion and avoid toxic accumulation of pseudopaline in the cytoplasm. The two following tasks will focus on the sequential and specific recognition and transport of pseudopaline across the inner and outer membranes, respectively ensured by the inner membrane exporter CntI and the general efflux pump MexAB-OprM, altogether constituting an unprecedented two-steps pseudopaline secretion pathway. The last task will explore one of the ultimate steps of the cycle, i.e. the recovery of pseudopaline from the medium by a specific outer membrane receptor CntO.
All the questions raised in this project will be addressed by combining the complementary expertise of the three partners in, P. aeruginosa and pseudopaline in vivo biology (P1), in vitro biochemistry and reconstitution of pseudopaline synthesis and transport (P2), and membrane transporters structural biology (P3).
The data acquired during the project will certainly provide important molecular clues on the different sequential mechanisms underlying the synthesis, secretion and recovery of pseudopaline. Our ambition is that this project will not only expand our knowledge on bacterial envelope trafficking of an important metallophore, but also pave the way for the development of suitable antibacterials against P. aeruginosa such as inhibitors of pseudopaline’s transporters or zincophore/antibiotic conjugates.