Copper homeostasis networks in the bacterium Pseudomonas aeruginosa

Abstract

Bacterial copper (Cu) homeostasis enables both precise metallation of diverse cuproproteins and control of variable metal levels. To this end, protein networks mobilize Cu to cellular targets with remarkable specificity. However, the understanding of these processes is rather fragmented. Here, we use genome-wide transcriptomic analysis by RNA-Seq to characterize the response of to external 0.5 mm CuSO, a condition that did not generate pleiotropic effects. Pre-steady-state (5-min) and steady-state (2-h) Cu fluxes resulted in distinct transcriptome landscapes. Cells quickly responded to Cu stress by slowing down metabolism. This was restored once steady state was reached. Specific Cu homeostasis genes were strongly regulated in both conditions. Our system-wide analysis revealed induction of three Cu efflux systems (a P-ATPase, a porin, and a resistance-nodulation-division (RND) system) and of a putative Cu-binding periplasmic chaperone and the unusual presence of two cytoplasmic CopZ proteins. Both CopZ chaperones could bind Cu with high affinity. Importantly, novel transmembrane transporters probably mediating Cu influx were among those largely repressed upon Cu stress. Compartmental Cu levels appear independently controlled; the cytoplasmic Cu sensor CueR controls cytoplasmic chaperones and plasma membrane transporters, whereas CopR/S responds to periplasmic Cu Analysis of Δ and Δ mutant strains revealed a CopR regulon composed of genes involved in periplasmic Cu homeostasis and its putative DNA recognition sequence. In conclusion, our study establishes a system-wide model of a network of sensors/regulators, soluble chaperones, and influx/efflux transporters that control the Cu levels in compartments.

Antibacterial effect of TiO2:Cu:Ag thin coatings on Pseudomonas strain measured by microbiological and ATP assays

“…The bacteriostatic effect and adaptation of Pseudomonas DSM50026 to the tested annealed nanomaterials could be explained by the ability of this bacterial species to activate special transport pumps for an export of the nanoparticles or ions out of the cell. This fact is a possible mechanism of stress response as other researchers have reported .…”

A Copper Relay System Involving Two Periplasmic Chaperones Drives cbb3-Type Cytochrome c Oxidase Biogenesis in Rhodobacter capsulatus

“…10,30,31 The affinities of R. capsulatus SenC and PccA for Cu(I) were determined using a competition assay with bathocuproine disulfonate (BCS) as described previously 29,32 (Figure 4b). Briefly, 10 μ M Cu(II) was reduced with 10 μ M ascorbic acid and incubated with 25 μ M BCS, and the [Cu I (BCS) 2 ] 3− complex (Cu-BCS) thus formed was titrated with different SenC or PccA concentrations varying from 0 to 20 μ M. The decrease in Cu-BCS with increasing total protein concentration was monitored at 483 nm, and the competition $K_{\mathrm{normalD}}^{\text{Cu}(\mathrm{I})}$ values were determined as described in the Supporting Information.…”

An important role for periplasmic storage in Pseudomonas aeruginosa copper homeostasis revealed by a combined experimental and computational modeling study

“…Several proteins that play a role in copper sensing, transfer, and distribution between compartments have been identified in the periplasm, cytoplasm, inner and outer membranes of Pseudomonas aeruginosa (Yoneyama and Nakae, ; Teitzel et al, ; Caille et al, ; Frangipani and Haas, ; Thaden et al, ; González‐Guerrero et al, ; Elsen et al, ; Quintana et al, ). Extracellular Cu 2+ likely enters the periplasm through OprC, an outer membrane porin (Yoneyama and Nakae, ).…”

“…While OprC binds Cu 2+ , the specificity of transport as well as the putative presence of external reductases generating Cu + has not been established. The inner membrane CcoA transports into the cytoplasm the periplasmic copper destined to metalate cytochrome c oxidase (Ekici et al, ), while novel members of the Major Facilitator Superfamily might also enable copper influx through this membrane (Quintana et al, ). Copper is likely supplied to cytoplasmic cuproproteins and other putative copper binging pools via cytoplasmic chaperones, as has been proposed for the role of chaperones in delivering the metal to inner membrane Cu+ exporters (P1B‐ATPases) and transcriptional sensors (Cobine et al, ; González‐Guerrero et al, ).…”