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Copper resistance is essential for virulence of Mycobacterium tuberculosis.

ABSTRACT: Copper (Cu) is essential for many biological processes, but is toxic when present in excessive amounts. In this study, we provide evidence that Cu plays a crucial role in controlling tuberculosis. A Mycobacterium tuberculosis (Mtb) mutant lacking the outer membrane channel protein Rv1698 accumulated 100-fold more Cu and was more susceptible to Cu toxicity than WT Mtb. Similar phenotypes were observed for a M. smegmatis mutant lacking the homolog Ms3747, demonstrating that these mycobacterial copper transport proteins B (MctB) are essential for Cu resistance and maintenance of low intracellular Cu levels. Guinea pigs responded to infection with Mtb by increasing the Cu concentration in lung lesions. Loss of MctB resulted in a 1,000- and 100-fold reduced bacterial burden in lungs and lymph nodes, respectively, in guinea pigs infected with Mtb. In mice, the persistence defect of the Mtb mctB mutant was exacerbated by the addition of Cu to the diet. These experiments provide evidence that Cu is used by the mammalian host to control Mtb infection and that Cu resistance mechanisms are crucial for Mtb virulence. Importantly, Mtb is much more susceptible to Cu than other bacteria and is killed in vitro by Cu concentrations lower than those found in phagosomes of macrophages. Hence, this study reveals an Achilles heel of Mtb that might be a promising target for tuberculosis chemotherapy.

SUBMITTER: Wolschendorf F

PROVIDER: S-EPMC3029754 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Copper resistance is essential for virulence of Mycobacterium tuberculosis.

Wolschendorf Frank F Ackart David D Shrestha Tej B TB Hascall-Dove Laurel L Nolan Scott S Lamichhane Gyanu G Wang Ying Y Bossmann Stefan H SH Basaraba Randall J RJ Niederweis Michael M

Proceedings of the National Academy of Sciences of the United States of America 20110104 4

Copper (Cu) is essential for many biological processes, but is toxic when present in excessive amounts. In this study, we provide evidence that Cu plays a crucial role in controlling tuberculosis. A Mycobacterium tuberculosis (Mtb) mutant lacking the outer membrane channel protein Rv1698 accumulated 100-fold more Cu and was more susceptible to Cu toxicity than WT Mtb. Similar phenotypes were observed for a M. smegmatis mutant lacking the homolog Ms3747, demonstrating that these mycobacterial cop ...[more]

PMID: 21205886

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Project description:Purpose: CsoR, a copper responsive negative regulator of Mycobacterium tuberculosis has been shown to respond to copper and bind to its own regulon in in vitro experiments. Here we examine the role of CsoR in vivo by examining the impact of deletion of csoR on the host transcriptome. Methods: csoR was knocked out of M. tuberculosis H37Rv using the specialized transduction method developed by Bardarov et al (2002), followed by removal of the hygromycin marker with plasmid pYUB870. Both wild type and confirmed csoR knockout were grown in copper free Sauton's media to late log phase before harvesting for transcriptomic studies. RNA was extracted using a modified Trizol method prior to DNAse treatment and rRNA depletion. Sequencing was done on an Illumina HiSeq 2000, filtered for quality using the FASTX-Toolkit, and mapped using Bowtie, and counts per locus generated with BedTools in the Galaxy platform. Differential expression analysis was carried out in edgeR with significantly differentially expressed genes being identified as those with ≥|2| fold differential expression between ΔcsoR and wild type strains, and an FDR < 0.05. Results: We found that 223 genes were differentially expressed between the ΔcsoR and wild type strains, 52 induced and 71 repressed. Differential expression of 10 of these genes, 6 induced and 4 repressed, was confirmed by qRT-PCR using SYBR green methodology. The only copper responsive genes identified were those within the csoR operon: csoR, Rv0968, ctpV, Rv0970, suggesting that csoR may only regulate its own operon in response to copper. Genes in the RicR regulon, another copper responsive transcriptional regulator, were not significantly differentially expressed, but some of these copper inducible genes were slightly down regulated suggesting that copper levels may be lower in the mutant strain as compared to wild type. Notably, 44 of the 48 members of the dosR regulon, responsive to hypoxic and NO stress, were induced in the mutant vs wild type suggesting that csoR is necessary for maintaining homeostasis, likely through copper regulation, within the cell. Conclusions: We have shown that CsoR is likely only directly regulating its own operon in response to copper, however it is required to maintain homeostasis, preventing a hypoxia-type stress response in the absense of copper.

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Copper resistance is essential for virulence of Mycobacterium tuberculosis.

Publications

Copper resistance is essential for virulence of Mycobacterium tuberculosis.

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