Pseudomonas aeruginosa CDF transporters CzcD and YiiP are involved in Zn2+ efflux, outer membrane permeability and antibiotic resistance

RAIMUNDA D.; SALUSSO A.

New Orleans

Congreso; Biophysical Society 61th Annual Meeting; 2017

Transporters of the cation diffusion facilitator (CDF) family form dimers that export transition metals from the cytosol. The opportunistic pathogen Pseudomonas aeruginosa presents three homologous CDF genes, czcD, cotP and yiiP. CotP appears to have a role in Co2+ homeostasis as the deletion mutant strain ∆cotP is more sensitive and accumulate this ion. In inhibition halo experiments, ∆czcD and ∆yiiP strains showed low Zn2+ sensitivity. However, in iron-rich media and in the presence of Zn2+ the strains secreted higher levels of the iron chelator pyoverdine. The non-pyoverdine producer triple mutants, ∆zntA-∆pvdA-∆czcD and ∆zntA-∆pvdA-∆yiiP, displayed increased Zn2+ sensitivity and increased intracellular Zn2+ accumulation compared to the double mutant ∆zntA-∆pvdA. Most importantly, the strains ∆czcD, ∆yiiP, ∆pvdA-∆czcD and ∆pvdA-∆yiiP showed a 4- to 8-fold increased sensitivity to imipenem and ciprofloxacin and a 2-fold increased sensitivity to chloramphenicol and gentamycin. Complemented strains attained similar levels of antibiotic resistance as the PAO1 parental strain. These observations correlated with increased sensitivity to EDTA-lysozyme treatment and overexpression of OprN and OprD porins in ∆czcD and ∆yiiP vs. WT and ∆cotP. We hypothesize that while CotP is a Co2+ efflux transporter CzcD and YiiP export Zn2+ to the periplasm and that their function is required for regulation of OprD synthesis, outer membrane stability and therefore antibiotic tolerance.