A periplasmic metallochaperone of the cation diffusion facilitator YIIP is required of Zn2+ sensing in Pseudomonas aeruginosa

MIHELJ, PAULA; MOREYRA, TOMÁS; CARRIZO, MARÍA E.; RAIMUNDA, DANIEL

Los Cocos, Córdoba, Argentina

Congreso; XVII Congreso Argentino de Microbiología General (SAMIGE); 2022

Asociación Argentina de Microbiología General (SAMIGE)

Transition metals (TM) are fundamental in the cellular physiology of all living organisms. Zinc is one of them as it participates as an enzyme co-factor and in signaling pathways. Thus, cells require a fine tuning of the metal allocation. Zn2+ transporters assisted by metallochaperones are key players in this process, and in gram-negative bacteria, YiiP, a member of the Cation Diffusion Facilitator (CDF) family exports Zn2+ from the cytosol to the periplasm. However, there is yet no evidence of a partnering metallochaperone. Here we provide evidences that in Pseudomonas aeruginosa, YiiP/PA3963 participates in a Zn-dependent signaling pathways assisted by a metallochaperone encoded by the PA3962 locus. Bioinformatic studies showed that PA3962 displays a 3D structural similarity with both CopZ, a Cu+ metallochaperone from Bacillus subtilis, and the N-terminal soluble domain of Zn2+-PIBATPases. A BLAST analysis shows that this protein is unique in the clade of Pseudomonadales. Several amino acids candidates for divalent TM coordination were identified. In order to assess the functional role of PA3962 we performed TM (Co2+, Fe2+, Mn2+, Ni2+, Zn2+) binding assay using PAR (4-(2-Pyridylazo) resorcinol) colorimetric assay and observed a preference for Zn2+ binding with a 1:1 stoichiometry. Due to the role of the periplasmic Zn2+ -sensing system CzcS-CzcR in imipenem resistance associated to OprD transcriptional regulation described in P. aeruginosa we tested the response of the insertional mutant PA3962::Tn5 strain to this antibiotic and observed an increased sensitivity like previously described in yiiP::Tn5. This sensitivity decreased in yiiP::Tn5 in the presence of Zn2+ while PA3962::Tn5 seemed insensitive to the TM. In light of these results, we propose that PA3962, hereafter periplasmic metallochaperone of YiiP (PmcY) facilitates Zn2+ sensing by the two-component system CzcR/CzcS.