Zinc and copper toxicity in host defense against pathogens: Mycobacterium tuberculosis as a model example of an emerging paradigm.
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ABSTRACT:
SUBMITTER: Neyrolles O
PROVIDER: S-EPMC3841717 | biostudies-literature | 2013
REPOSITORIES: biostudies-literature
Publications
Zinc and copper toxicity in host defense against pathogens: Mycobacterium tuberculosis as a model example of an emerging paradigm.
Neyrolles Olivier O Mintz Elisabeth E Catty Patrice P
Frontiers in cellular and infection microbiology 20131127
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Project description:Copper (Cu) ions are likely the most important immunological metal-related toxin utilized in controlling bacterial infections. Impairment of bacterial Cu resistance reduces viability within the host. Thus, pharmacological enhancement of Cu-mediated antibacterial toxicity may lead to novel strategies in drug discovery and development. Screening for Cu toxicity-enhancing antibacterial molecules identified 8-hydroxyquinoline (8HQ) to be a potent Cu-dependent bactericidal inhibitor of Mycobacterium tuberculosis The MIC of 8HQ in the presence of Cu was 0.16 μM for replicating and nonreplicating M. tuberculosis cells. We found 8HQ's activity to be dependent on the presence of extracellular Cu and to be related to an increase in cell-associated labile Cu ions. Both findings are consistent with 8HQ acting as a Cu ionophore. Accordingly, we identified the 1:1 complex of 8HQ and Cu to be its active form, with Zn, Fe, or Mn neither enhancing nor reducing its Cu-specific action. This is remarkable, considering that the respective metal complexes have nearly identical structures and geometries. Finally, we found 8HQ to kill M. tuberculosis selectively within infected primary macrophages. Given the stark Cu-dependent nature of 8HQ activity, this is the first piece of evidence that Cu ions within macrophages may bestow antibacterial properties to a Cu-dependent inhibitor of M. tuberculosis In conclusion, our findings highlight the metal-binding ability of the 8-hydroxyquinoline scaffold to be a potential focus for future medicinal chemistry and highlight the potential of innate immunity-inspired screening platforms to reveal molecules with novel modes of action against M. tuberculosis.
| S-EPMC5038248 | biostudies-literature
Project description:The purpose of this study was to determine the transcriptomes of Mycobacterium tuberculosis m2 6206 (Mtb) exposed to varying concentration of zinc (Zn2+) in vitro that mimic the concentrations of Zn2+ experienced in vivo during infection. Mtb were grown in the chemically defined Sauton's medium without Zn2+ added until expression of Zur-regulated genes were observed, indicating the onset of Zn-limitation. Cells were then treated with with different concentrations of Zn2+ through addition of 500 uM Zn2+, 6uM Zn2+, no added Zn2+, 0.35 mg/mL recombinant calprotectin (CP) or 0.8 µM N,N,N′,N′-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN). After 24 hours of exposure to the different [Zn2+] conditions, RNA was harvested, prepared for RNA-seq, and sequenced on the Illumina HiSeq platform with a paired-end (2x150bp) configuration.
2021-04-21 | GSE168659 | GEO
Project description:Copper (Cu) is a trace element essential for the growth and development of almost all organisms, including bacteria. However, Cu overload in most systems is toxic. Studies show Cu accumulates in macrophage phagosomes infected with bacteria, suggesting Cu provides an innate immune mechanism to combat invading pathogens. To counteract the host-supplied Cu, increasing evidence suggests that bacteria have evolved Cu resistance mechanisms to facilitate their pathogenesis. In particular, Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, has evolved multiple pathways to respond to Cu. Here, we summarize what is currently known about Cu homeostasis in Mtb and discuss potential sources of Cu encountered by this and other pathogens in a mammalian host.
| S-EPMC4465026 | biostudies-literature
Project description:Mycobacterium tuberculosis H37Rv (Mtb) was grown in Sauton's medium with and without added zinc. Cultures were grown for 10 days and RNA was harvested from TRIzol extractions.
2021-04-21 | GSE168513 | GEO
Project description:In this study, we report the identification and characterization of several regulators in Mycobacterium tuberculosis.
2010-09-29 | GSE23947 | GEO
Project description:In this study, we report the identification of a five-locus copper-inducible regulon in Mycobacterium tuberculosis. The identification of a copper responsive regulon unique to pathogenic Mycobacteria suggests copper homeostasis must be maintained during an infection.
2010-10-27 | GSE23498 | GEO
Project description:Copper resistance mechanisms are crucial for many pathogenic bacteria, including Mycobacterium tuberculosis, during infection because the innate immune system utilizes copper ions to kill bacterial intruders. Despite several studies detailing responses of mycobacteria to copper, the pathways by which copper ions cross the mycobacterial cell envelope are unknown. Deletion of porin genes in Mycobacterium smegmatis leads to a severe growth defect on trace copper medium but simultaneously increases tolerance for copper at elevated concentrations, indicating that porins mediate copper uptake across the outer membrane. Heterologous expression of the mycobacterial porin gene mspA reduced growth of M. tuberculosis in the presence of 2.5 ?M copper by 40% and completely suppressed growth at 15 ?M copper, while wild-type M. tuberculosis reached its normal cell density at that copper concentration. Moreover, the polyamine spermine, a known inhibitor of porin activity in Gram-negative bacteria, enhanced tolerance of M. tuberculosis for copper, suggesting that copper ions utilize endogenous outer membrane channel proteins of M. tuberculosis to gain access to interior cellular compartments. In summary, these findings highlight the outer membrane as the first barrier against copper ions and the role of porins in mediating copper uptake in M. smegmatis and M. tuberculosis.
| S-EPMC3811576 | biostudies-literature
Project description:Mycobacterium tuberculosis H37Rv (Mtb) grown in chemically defined medium replete for Zinc and limited for Zinc
2021-04-23 | PXD024389 | Pride
Project description:Copper and zinc homeostasis systems in pathogenic bacteria are required to resist host efforts to manipulate the availability and toxicity of these metal ions. Central to this microbial adaptive response is the involvement of metal-trafficking and metal-sensing proteins that ultimately exercise control of metal speciation in the cell. Cu-specific and Zn-specific metalloregulatory proteins regulate the transcription of metal-responsive genes while metallochaperones and related proteins ensure that these metals are appropriately buffered by the intracellular milieu and delivered to correct intracellular targets. In this review, we summarize recent findings on how bacterial pathogens mount a metal-specific response to derail host efforts to win the 'fight over metals.'
| S-EPMC4008645 | biostudies-literature
Project description:Mycobacterium tuberculosis (Mtb) has complex and dynamic interactions with the human host, and subpopulations of Mtb that emerge during infection can influence disease outcomes. This study implicates zinc ion (Zn2+) availability as a likely driver of bacterial phenotypic heterogeneity in vivo. Zn2+ sequestration is part of "nutritional immunity", where the immune system limits micronutrients to control pathogen growth, but this defense mechanism seems to be ineffective in controlling Mtb infection. Nonetheless, Zn2+-limitation is an environmental cue sensed by Mtb, as calprotectin triggers the zinc uptake regulator (Zur) regulon response in vitro and co-localizes with Zn2+-limited Mtb in vivo. Prolonged Zn2+ limitation leads to numerous physiological changes in vitro, including differential expression of certain antigens, alterations in lipid metabolism and distinct cell surface morphology. Furthermore, Mtb enduring limited Zn2+ employ defensive measures to fight oxidative stress, by increasing expression of proteins involved in DNA repair and antioxidant activity, including well described virulence factors KatG and AhpC, along with altered utilization of redox cofactors. Here, we propose a model in which prolonged Zn2+ limitation defines a population of Mtb with anticipatory adaptations against impending immune attack, based on the evidence that Zn2+-limited Mtb are more resistant to oxidative stress and exhibit increased survival and induce more severe pulmonary granulomas in mice. Considering that extracellular Mtb may transit through the Zn2+-limited caseum before infecting naïve immune cells or upon host-to-host transmission, the resulting phenotypic heterogeneity driven by varied Zn2+ availability likely plays a key role during early interactions with host cells.
| S-EPMC8121289 | biostudies-literature