Efficient zinc uptake is critical for the ability of Pseudomonas aeruginosa to express virulence traits and colonize the human lung.

We have recently shown that Pseudomonas aeruginosa, an opportunistic pathogen that chronically infects the lungs of patients with cystic fibrosis (CF) and other forms of lung disease, is extremely efficient in recruiting zinc from the environment and that this capability is required for its ability to cause acute lung infections in mice. To verify that P. aeruginosa faces zinc shortage when colonizing the lungs of human patients, we analyzed the expression of three genes that are highly induced under conditions of zinc deficiency (zrmA, dksA2 and rpmE2), in bacteria in the sputum of patients with inflammatory lung disease.

Growth of Pseudomonas aeruginosa in zinc poor environments is promoted by a nicotianamine-related metallophore.

Previous studies have suggested that P. aeruginosa possesses redundant zinc uptake systems. To identify uncharacterized zinc transporters, we analyzed the genome-wide transcriptional responses of P.

Prosurvival AMBRA1 turns into a proapoptotic BH3-like protein during mitochondrial apoptosis.

Autophagy and apoptosis are 2 stress-response mechanisms that are closely interconnected. However, the molecular interplays between these 2 pathways remain to be clarified. Here we report that the crucial proautophagic factor AMBRA1 can act as a positive mediator of mitochondrial apoptosis.

An ERp57-mediated disulphide exchange promotes the interaction between Burkholderia cenocepacia and epithelial respiratory cells.

Previous studies have demonstrated that extracellular glutathione reduces the ability of the Cystic Fibrosis pathogen Burkholderia cenocepacia to infect primary or immortalized epithelial respiratory cells. We report here that the adhesion and invasion ability of B. cenocepacia is limited also by thiol-oxidizing and disulphide-reducing agents and by protein disulfide isomerase (PDI) inhibitors.

AMBRA1 and BECLIN 1 interplay in the crosstalk between autophagy and cell proliferation.

Autophagy-promoting proteins and stimuli are often associated with inhibition of cell proliferation; in this context, we recently described a key role for the pro-autophagic protein AMBRA1. Indeed, AMBRA1, through its direct interaction with the protein phosphatase PP2A, tightly regulates the stability of the oncoprotein and pro-mitotic factor c-Myc. Moreover, the AMBRA1-mediated regulation of c-Myc affects both cell proliferation rate and tumorigenesis.

The capability of Pseudomonas aeruginosa to recruit zinc under conditions of limited metal availability is affected by inactivation of the ZnuABC transporter.

The ability of a large number of bacterial pathogens to multiply in the infected host and cause disease is dependent on their ability to express high affinity zinc importers. In many bacteria, ZnuABC, a transporter of the ABC family, plays a central role in the process of zinc uptake in zinc poor environments, including the tissues of the infected host. To initiate an investigation into the relevance of the zinc uptake apparatus for Pseudomonas aeruginosa pathogenicity, we have generated a znuA mutant in the PA14 strain.

Proteomic and ionomic profiling reveals significant alterations of protein expression and calcium homeostasis in cystic fibrosis cells.

Cystic fibrosis (CF) is an autosomal recessive disorder associated with mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene and defective chloride transport across the epithelial cell membranes. Abnormal epithelial ion transport is the primary cause of persistent airway infections and chronic inflammation in CF patients. In order to gain further insight into the mechanisms of epithelial dysfunctions linked to CFTR mutations, we performed and integrated proteomic and ionomic analysis of human bronchial epithelial IB3-1 cells and compared them with a CFTR-complemented isogenic cell line (C38).

Extracellular glutathione decreases the ability of Burkholderia cenocepacia to penetrate into epithelial cells and to induce an inflammatory response.

Background: The airway surface liquid (ASL) of Cystic Fibrosis (CF) patients contains a lower concentration of reduced glutathione (GSH) with respect to healthy people. It is not known whether this defect may favor lung colonization by opportunistic pathogens.

Principal Findings: We have analyzed the effects of extracellular GSH on the ability of Burkholderia cenocepacia to penetrate and multiply in epithelial respiratory cells.

Reactive oxygen species and epidermal growth factor are antagonistic cues controlling SHP-2 dimerization.

The SHP-2 tyrosine phosphatase plays key regulatory roles in the modulation of the cell response to growth factors and cytokines. Over the past decade, the integration of genetic, biochemical, and structural data has helped in interpreting the pathological consequences of altered SHP-2 function. Using complementary approaches, we provide evidence here that endogenous SHP-2 can dimerize through the formation of disulfide bonds that may also involve the catalytic cysteine.

Thermal stability and redox properties of M. tuberculosis CuSOD.

The superoxide dismutase from Mycobacterium tuberculosis is the only Cu-containing superoxide dismutase that lacks zinc in the active site. To explore the structural properties of this unusual enzyme, we have investigated its stability by differential scanning calorimetry. We have found that the holo-enzyme is significantly more stable than the apo-protein or the partially metallated enzyme, but that its melting temperature is markedly lower than that of all the other characterized eukaryotic and prokaryotic Cu,Zn superoxide dismutases.

Structural basis of heme binding in the Cu,Zn superoxide dismutase from Haemophilus ducreyi.

The Cu,Zn superoxide dismutase from Haemophilus ducreyi is characterized by the unique ability to bind heme at its dimer interface. Here we report the high-resolution crystal structures of this protein in the heme-loaded (holo) and heme-free (apo) forms. Heme is asymmetrically bound between the two enzyme subunits, where heme iron is coordinated by two histidine residues, His64 and His 124, provided by the two subunits.

Regulatory and structural properties differentiating the chromosomal and the bacteriophage-associated Escherichia coli O157:H7 Cu, Zn superoxide dismutases.

Background: Highly virulent enterohemorrhagic Escherichia coli O157:H7 strains possess three sodC genes encoding for periplasmic Cu, Zn superoxide dismutases: sodC, which is identical to the gene present in non-pathogenic E. coli strains, and sodC-F1 and sodC-F2, two nearly identical genes located within lambdoid prophage sequences. The significance of this apparent sodC redundancy in E.

Distinctive functional features in prokaryotic and eukaryotic Cu,Zn superoxide dismutases.

Bacterial and eukaryotic Cu,Zn superoxide dismutases show remarkable differences in the active site region and in their quaternary structure organization. We report here a functional comparison between four Cu,Zn superoxide dismutases from Gram-negative bacteria and the eukaryotic bovine enzyme. Our data indicate that bacterial dimeric variants are characterized by catalytic rates higher than that of the bovine enzyme, probably due to the solvent accessibility of their active site.

Induction of apoptosis and release of interleukin-1 beta by cell wall-associated 19-kDa lipoprotein during the course of mycobacterial infection.

Mycobacterium tuberculosis induces apoptosis in human monocyte-derived macrophages (MDMs) during the early stages of infection. We investigated the proapoptotic role of cell wall-associated mycobacterial 19-kDa lipoprotein and the possible association between 19-kDa lipoprotein signaling and production of proinflammatory cytokines. Purified mycobacterial 19-kDa lipoprotein, 19-kDa lipoprotein-expressing M.

Unique features of the sodC-encoded superoxide dismutase from Mycobacterium tuberculosis, a fully functional copper-containing enzyme lacking zinc in the active site.

The sodC-encoded Mycobacterium tuberculosis superoxide dismutase (SOD) shows high sequence homology to other members of the copper/zinc-containing SOD family. Its three-dimensional structure is reported here, solved by x-ray crystallography at 1.63-A resolution.