Interplay between manganese and zinc homeostasis in the human pathogen Streptococcus pneumoniae

Jacobsen, Faith E.; Kazmierczak, Krystyna M.; Lisher, John P.; Winkler, Malcolm E.; Giedroc, David P.

doi:10.1039/c0mt00050g

Cited by 111 publications

(160 citation statements)

References 21 publications

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“…Despite not encoding any known copper utilization proteins, the pneumococcus contains a significant amount of this elementapproximately 20 percent of the level of manganese, corresponding to approximately 100 nanograms of copper per milligram of cellular protein (45). While not having a known copper import mechanism, all sequenced pneumococci encode a highly efficient copper efflux system.…”

Section: Discussionmentioning

confidence: 99%

Role of Copper Efflux in Pneumococcal Pathogenesis and Resistance to Macrophage-Mediated Immune Clearance

et al. 2015

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In bacteria, the intracellular levels of metals are mediated by tightly controlled acquisition and efflux systems. This is particularly true of copper, a trace element that is universally toxic in excess. During infection, the toxic properties of copper are exploited by the mammalian host to facilitate bacterial clearance. To better understand the role of copper during infection, we characterized the contribution of the cop operon to copper homeostasis and virulence in Streptococcus pneumoniae. Deletion of either the exporter, encoded by copA, or the chaperone, encoded by cupA, led to hypersensitivity to copper stress. We further demonstrated that loss of the copper exporter encoded by copA led to decreased virulence in pulmonary, intraperitoneal, and intravenous models of infection. Deletion of copA resulted in enhanced macrophage-mediated bacterial clearance in vitro. The attenuation phenotype of the copA mutant in the lung was found to be dependent on pulmonary macrophages, underscoring the importance of copper efflux in evading immune defenses. Overall, these data provide insight into the role of the cop operon in pneumococcal pathogenesis.

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Section: Discussionmentioning

confidence: 99%

Role of Copper Efflux in Pneumococcal Pathogenesis and Resistance to Macrophage-Mediated Immune Clearance

et al. 2015

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“…It is a cofactor for a number of essential prokaryotic enzymes and transcriptional regulators (19). In the human body, the zinc concentration varies from 1.5 M in cerebrospinal fluid to over 100 M in lung tissue (20,21). Pathogenic bacteria must adapt zinc transport mechanisms to accommodate these differences to both avoid toxicity and meet their requirements for this metal.…”

Section: S Treptococcus Agalactiae (Group B Streptococcus [Gbs]) Is Amentioning

confidence: 99%

The Adc/Lmb System Mediates Zinc Acquisition in Streptococcus agalactiae and Contributes to Bacterial Growth and Survival

et al. 2016

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The Lmb protein of Streptococcus agalactiae is described as an adhesin that binds laminin, a component of the human extracellular matrix. In this study, we revealed a new role for this protein in zinc uptake. We also identified two Lmb homologs, AdcA and AdcAII, redundant binding proteins that combine with the AdcCB translocon to form a zinc-ABC transporter. Expression of this transporter is controlled by the zinc concentration in the medium through the zinc-dependent regulator AdcR. Triple deletion of lmb, adcA, and adcAII, or that of the adcCB genes, impaired growth and cell separation in a zinc-restricted environment. Moreover, we found that this Adc zinc-ABC transporter promotes S. agalactiae growth and survival in some human biological fluids, suggesting that it contributes to the infection process. These results indicated that zinc has biologically vital functions in S. agalactiae and that, under the conditions tested, the Adc/Lmb transporter constitutes the main zinc acquisition system of the bacterium. IMPORTANCEA zinc transporter, composed of three redundant binding proteins (Lmb, AdcA, and AdcAII), was characterized in Streptococcus agalactiae. This system was shown to be essential for bacterial growth and morphology in zinc-restricted environments, including human biological fluids. S treptococcus agalactiae (group B streptococcus [GBS]) is aGram-positive commensal bacterium of the human gastrointestinal and uro-genital tracts. GBS carriage is mostly asymptomatic in healthy adults, and this bacterium is detected in the vagina of approximatively 30% of pregnant women. Maternal carriage is the main source of transmission to neonates, in which S. agalactiae can cause invasive infections (pneumonia, septicemia, and meningitis), with an overall mortality rate of approximately 10% (1, 2). GBS is also an emergent pathogen among the elderly and in adults with underlying diseases (1, 3).The ability of GBS to colonize different niches and cause infection is multifactorial, and many virulence-associated proteins have been identified (4, 5). Binding of GBS adhesins to components of the extracellular matrix constitutes a crucial first step in the process of infection (6-9). Among them, the Lmb protein has been identified as a GBS receptor for laminin, a glycosylated multidomain protein found in all human tissues (10). The gene encoding Lmb is located on a transposon with the scpB and sht genes, which encode a C5a peptidase and a histidine triad protein, respectively (11, 12). The lmb promoter region is a hot spot for the integration of two mobile genetic elements. One of them is associated with increased expression of lmb, resulting in increased binding of strains harboring the transposon to laminin (13). It has also been shown that Lmb may promote bacterial invasion in human brain microvascular endothelial cell lines (14).Lmb is clustered by sequence homology as a metal-binding receptor. Indeed, Lmb has strong homology with the zinc-binding proteins AdcA and Lbp of other streptococcal species (15, 16). Th...

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“…The total cellassociated Zn or Mn was quantified from 5-ml cultures that had been grown in BHI medium for 2 h with or without 0.2 mM ZnSO 4 or MnCl 2 and analyzed essentially as described previously (34). Briefly, cells were centrifuged, washed once with ice-cold 1ϫ phosphate-buffered saline (PBS), pH 7.4, containing 2 mM NTA, washed twice with ice-cold 1ϫ metal-free PBS (10 g/liter Chelex-100 resin was used to remove the metals), and dried overnight using a centrifuge evaporator.…”

Section: Methodsmentioning

confidence: 99%

“…Previous studies have consistently shown that pneumococcal cells lacking czcD are specifically sensitive to Zn toxicity, while mntE mutants are sensitive to Mn overload (21,22,34,35). During metal stress, czcD and mntE mutants accumulate Zn and Mn, respectively.…”

mentioning

confidence: 99%

“…In addition to T. thermophilus CzrB and M. gryphiswaldense MamM, functional homologs of E. coli YiiP have been identified in a number of microorganisms, including Shewanella oneidensis YiiP, Ralstonia metallidurans CzcD, Staphylococcus aureus CzrB, Deinococcus radiodurans MntE, Rhizobium etli EmfA, and Streptococcus pneumoniae CzcD and MntE (20,21,23,(30)(31)(32)(33)(34)(35). Previous studies have consistently shown that pneumococcal cells lacking czcD are specifically sensitive to Zn toxicity, while mntE mutants are sensitive to Mn overload (21,22,34,35).…”

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confidence: 99%

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Functional Determinants of Metal Ion Transport and Selectivity in Paralogous Cation Diffusion Facilitator Transporters CzcD and MntE in Streptococcus pneumoniae

Martin

Giedroc

2016

J Bacteriol

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Cation diffusion facilitators (CDFs) are a large family of divalent metal transporters that collectively possess broad metal specificity and contribute to intracellular metal homeostasis and virulence in bacterial pathogens. Streptococcus pneumoniae expresses two homologous CDF efflux transporters, MntE and CzcD. Cells lacking mntE or czcD are sensitive to manganese (Mn) or zinc (Zn) toxicity, respectively, and specifically accumulate Mn or Zn, respectively, thus suggesting that MntE selectively transports Mn, while CzcD transports Zn. Here, we probe the origin of this metal specificity using a phenotypic growth analysis of pneumococcal variants. Structural homology to Escherichia coli YiiP predicts that both MntE and CzcD are dimeric and each protomer harbors four pairs of conserved metal-binding sites, termed the A site, the B site, and the C1/C2 binuclear site. We find that single amino acid mutations within both the transmembrane domain A site and the B site in both CDFs result in a cellular metal sensitivity similar to that of the corresponding null mutants. However, multiple mutations in the predicted cytoplasmic C1/C2 cluster of MntE have no impact on cellular Mn resistance, in contrast to the analogous substitutions in CzcD, which do have on impact on cellular Zn resistance. Deletion of the MntE-specific C-terminal tail, present only in Mn-specific bacterial CDFs, resulted in only a modest growth phenotype. Further analysis of MntE-CzcD functional chimeric transporters showed that Asn and Asp in the ND-DD A-site motif of MntE and the most N-terminal His in the HD-HD site A of CzcD (the specified amino acids are underlined) play key roles in transporter metal selectivity. IMPORTANCECation diffusion facilitator (CDF) proteins are divalent metal ion transporters that are conserved in organisms ranging from bacteria to humans and that play important roles in cellular physiology, from metal homeostasis and resistance to type I diabetes in vertebrates. The respiratory pathogen Streptococcus pneumoniae expresses two metal CDF transporters, CzcD and MntE. How CDFs achieve metal selectivity is unclear. We show here that CzcD and MntE are true paralogs, as CzcD transports zinc, while MntE selectively transports manganese. Through the use of an extensive collection of pneumococcal variants, we show that a primary determinant for metal selectivity is the A site within the transmembrane domain. This extends our understanding of how CDFs discriminate among transition metals. T ransition metals from manganese (Mn) to zinc (Zn) in the first row of the periodic table serve as essential cofactors in metalloenzymes that are required for many important cellular processes, including replication, regulation, and central metabolism, among all domains of life (1-3). Despite their importance, excess transition metals can impair bacterial growth. Excess iron (Fe) is harmful due to its participation in Fenton chemistry, which produces a highly reactive hydroxyl radical that can damage biomolecules (4-7). Other transition m...

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Interplay between manganese and zinc homeostasis in the human pathogen Streptococcus pneumoniae

Cited by 111 publications

References 21 publications

Role of Copper Efflux in Pneumococcal Pathogenesis and Resistance to Macrophage-Mediated Immune Clearance

Role of Copper Efflux in Pneumococcal Pathogenesis and Resistance to Macrophage-Mediated Immune Clearance

The Adc/Lmb System Mediates Zinc Acquisition in Streptococcus agalactiae and Contributes to Bacterial Growth and Survival

Functional Determinants of Metal Ion Transport and Selectivity in Paralogous Cation Diffusion Facilitator Transporters CzcD and MntE in Streptococcus pneumoniae

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