Genetic and physiological responses of <i>Bacillus subtilis</i> to metal ion stress

Moore, Charles M.; Gaballa, Ahmed; Hui, Monica P.; Ye, Rick W.; Helmann, John D.

doi:10.1111/j.1365-2958.2005.04642.x

Cited by 146 publications

(160 citation statements)

References 52 publications

(84 reference statements)

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“…Thus, Fur derepression under copper stress did not depend on changes in the total intracellular iron content. Due to the broad differences in intracellular copper levels under normal conditions and copper stress, it seemed unlikely that derepression was caused by direct effects on transcriptional regulation such as inactivation of the Fur repressor, as previously suggested (41). Thus, it was assumed that copper-mediated induction of Fur-dependent genes was related to more indirect changes in iron-dependent cellular processes.…”

Section: Vol 192 2010 Copper Stress and Iron Homeostasis In B Subtmentioning

confidence: 96%

“…While global effects of copper stress on the transcriptome level have been described for model bacteria such as Escherichia coli and Bacillus subtilis (28,41), detailed aspects of such connections have been studied so far mainly in E. coli. The multicopper oxidase CueO, a laccase-like enzyme present in the periplasm, which was suggested as the site of elevated oxidizable copper levels (35), is responsible for the oxidation of Cu(I) and also the siderophore enterobactin, which is a potential reductant for Cu(II) (17).…”

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confidence: 99%

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Copper Stress Affects Iron Homeostasis by Destabilizing Iron-Sulfur Cluster Formation in Bacillus subtilis

et al. 2010

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Copper and iron are essential elements for cellular growth. Although bacteria have to overcome limitations of these metals by affine and selective uptake, excessive amounts of both metals are toxic for the cells. Here we investigated the influences of copper stress on iron homeostasis in Bacillus subtilis, and we present evidence that copper excess leads to imbalances of intracellular iron metabolism by disturbing assembly of iron-sulfur cofactors. Connections between copper and iron homeostasis were initially observed in microarray studies showing upregulation of Fur-dependent genes under conditions of copper excess. This effect was found to be relieved in a csoR mutant showing constitutive copper efflux. In contrast, stronger Fur-dependent gene induction was found in a copper efflux-deficient copA mutant. A significant induction of the PerR regulon was not observed under copper stress, indicating that oxidative stress did not play a major role under these conditions. Intracellular iron and copper quantification revealed that the total iron content was stable during different states of copper excess or efflux and hence that global iron limitation did not account for copperdependent Fur derepression. Strikingly, the microarray data for copper stress revealed a broad effect on the expression of genes coding for iron-sulfur cluster biogenesis (suf genes) and associated pathways such as cysteine biosynthesis and genes coding for iron-sulfur cluster proteins. Since these effects suggested an interaction of copper and iron-sulfur cluster maturation, a mutant with a conditional mutation of sufU, encoding the essential iron-sulfur scaffold protein in B. subtilis, was assayed for copper sensitivity, and its growth was found to be highly susceptible to copper stress. Further, different intracellular levels of SufU were found to influence the strength of Fur-dependent gene expression. By investigating the influence of copper on cluster-loaded SufU in vitro, Cu(I) was found to destabilize the scaffolded cluster at submicromolar concentrations. Thus, by interfering with iron-sulfur cluster formation, copper stress leads to enhanced expression of cluster scaffold and target proteins as well as iron and sulfur acquisition pathways, suggesting a possible feedback strategy to reestablish cluster biogenesis.

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Section: Vol 192 2010 Copper Stress and Iron Homeostasis In B Subtmentioning

confidence: 96%

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confidence: 99%

Copper Stress Affects Iron Homeostasis by Destabilizing Iron-Sulfur Cluster Formation in Bacillus subtilis

et al. 2010

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“…Similarly, hnRNP E1 along with hnRNP E2 and hnRNP K associates with the neurofilament-M (NF-M) mRNA during postnatal development based on the relative abundance of either the hnRNPs or the NF-M mRNA, which is suggestive of a dynamic post-transcriptional regulon (Thyagarajan and Szaro 2008). The regulon assembly possibly happens during mRNA processing and subsequent export to the cytoplasm, in turn pre-deciding the fate of the transcripts (Moore et al 2005). Overall, such a model provides a rationale and energetically favorable framework for integrating functional diversity of hnRNP E1.…”

Section: Role Of Hnrnp E1 In Tumorigenesis and Cancer Progressionmentioning

confidence: 99%

Heterogeneous nuclear ribonucleoproteins (hnRNPs) in cellular processes: Focus on hnRNP E1's multifunctional regulatory roles

Chaudhury¹,

Chander²,

Howe³

2010

RNA

236

232

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Heterogeneous nuclear ribonucleoproteins (hnRNPs) comprise a family of RNA-binding proteins. The complexity and diversity associated with the hnRNPs render them multifunctional, involved not only in processing heterogeneous nuclear RNAs (hnRNAs) into mature mRNAs, but also acting as trans-factors in regulating gene expression. Heterogeneous nuclear ribonucleoprotein E1 (hnRNP E1), a subgroup of hnRNPs, is a KH-triple repeat containing RNA-binding protein. It is encoded by an intronless gene arising from hnRNP E2 through a retrotransposition event. hnRNP E1 is ubiquitously expressed and functions in regulating major steps of gene expression, including pre-mRNA processing, mRNA stability, and translation. Given its wide-ranging functions in the nucleus and cytoplasm and interaction with multiple proteins, we propose a posttranscriptional regulon model that explains hnRNP E1's widespread functional diversity.

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“…Some classes of nanomaterials use ferritin nanocages as templates (6). The protein nanocages self-assemble from fourhelix-bundle subunits into cages of two sizes: 12-subunit, hydrogen peroxide-consuming miniferritins of bacteria and archea, and 24-subunit maxiferritins of archea, bacteria, and higher organisms (3,4,7). Miniferritins may be the more primitive and are alternatively named DNA-binding proteins because some of them coat DNA.…”

mentioning

confidence: 99%

NMR reveals pathway for ferric mineral precursors to the central cavity of ferritin

Turano

Lalli

Felli

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

132

200

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Ferritin is a multimeric nanocage protein that directs the reversible biomineralization of iron. At the catalytic ferroxidase site two iron (II) ions react with dioxygen to form diferric species. In order to study the pathway of iron(III) from the ferroxidase site to the central cavity a new NMR strategy was developed to manage the investigation of a system composed of 24 monomers of 20 kDa each. The strategy is based on 13 C-13 C solution NOESY experiments combined with solid-state proton-driven 13 C-13 C spin diffusion and 3D coherence transfer experiments. In this way, 75% of amino acids were recognized and 35% sequence-specific assigned. Paramagnetic broadening, induced by iron(III) species in solution 13 C-13 C NOESY spectra, localized the iron within each subunit and traced the progression to the central cavity. Eight iron ions fill the 20-Å-long iron channel from the ferrous/dioxygen oxidoreductase site to the exit into the cavity, inside the four-helix bundle of each subunit, contrasting with short paths in models. Magnetic susceptibility data support the formation of ferric multimers in the iron channels. Multiple iron channel exits are near enough to facilitate high concentration of iron that can mineralize in the ferritin cavity, illustrating advantages of the multisubunit cage structure.¹³C direct detection | high molecular weight NMR | iron channels | solid-state NMR | paramagnetic NMR F erritins are a family of protein nanocages that concentrate iron in biominerals for controlled release and use in enzyme iron cofactors. A large cavity that occupies about 30% of the total protein volume at the center of the cage is the mineralization site of ferritin ferrihydrite. The importance of ferritin is illustrated by embryonic lethality of gene deletion in mammals (1) and resistance to oxidants in animals, plants, bacteria, and archea that reflects consumption of iron(II) and dioxygen or hydrogen peroxide (2-5). Some classes of nanomaterials use ferritin nanocages as templates (6). The protein nanocages self-assemble from fourhelix-bundle subunits into cages of two sizes: 12-subunit, hydrogen peroxide-consuming miniferritins of bacteria and archea, and 24-subunit maxiferritins of archea, bacteria, and higher organisms (3, 4, 7). Miniferritins may be the more primitive and are alternatively named DNA-binding proteins because some of them coat DNA.The first step in the conversion of iron(II) and dioxygen to ferric oxide mineral, in the 24-subunit maxiferritins, occurs at catalytic oxidoreductase (ferroxidase) sites in the center of each of the four-helix bundles, which have long axes oriented almost parallel to the protein surface (Fig. 1A). Each active site has residues contributed by each of the four helices (Fig. 1B) that create a diiron(II) site similar to the diiron cofactor sites in ribonucleotide reductases and stearoyl desaturases (8). When dioxygen, the second substrate, binds to the active site after iron(II) binding, diferric oxo products form via a diferric peroxo intermediate. The active site has...

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Genetic and physiological responses of Bacillus subtilis to metal ion stress

Abstract: SummaryMetal ion homeostasis is regulated principally by metalloregulatory proteins that control metal ion uptake, storage and efflux genes. We have used transcriptional profiling to survey Bacillus subtilis for genes that are rapidly induced by exposure to high levels of

Cited by 146 publications

References 52 publications

Copper Stress Affects Iron Homeostasis by Destabilizing Iron-Sulfur Cluster Formation in Bacillus subtilis

Copper Stress Affects Iron Homeostasis by Destabilizing Iron-Sulfur Cluster Formation in Bacillus subtilis

Heterogeneous nuclear ribonucleoproteins (hnRNPs) in cellular processes: Focus on hnRNP E1's multifunctional regulatory roles

NMR reveals pathway for ferric mineral precursors to the central cavity of ferritin

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