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  • 1
    Online Resource
    Online Resource
    Biodetection and bioremediation of copper ions in environmental water samples using a temperature-controlled, dual-functional Escherichia coli cell
    Springer Science and Business Media LLC ; 2019
    In:  Applied Microbiology and Biotechnology Vol. 103, No. 16 ( 2019-8), p. 6797-6807
    Details
    In: Applied Microbiology and Biotechnology, Springer Science and Business Media LLC, Vol. 103, No. 16 ( 2019-8), p. 6797-6807
    Type of Medium: Online Resource
    ISSN: 0175-7598 , 1432-0614
    URL: Article
    DOI: 10.1007/s00253-019-09984-9
    RVK:
    WA 15000
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 1464336-4
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Identification of an Intermediate Form of Ferredoxin That Binds Only Iron Suggests That Conversion to Holo-Ferredoxin Is Independent of the ISC System in Escherichia coli
    American Society for Microbiology ; 2021
    In:  Applied and Environmental Microbiology Vol. 87, No. 10 ( 2021-04-27)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 87, No. 10 ( 2021-04-27)
    Abstract: Escherichia coli [2Fe-2S]-ferredoxin and other ISC proteins encoded by the iscRSUA-hscBA-fdx-iscX ( isc ) operon are responsible for the assembly of iron-sulfur clusters. It is proposed that ferredoxin (Fdx) donates electrons from its reduced [2Fe-2S] center to iron-sulfur cluster biogenesis reactions. However, the underlying mechanisms of the [2Fe-2S] cluster assembly in Fdx remain elusive. Here, we report that Fdx preferentially binds iron, but not the [2Fe-2S] cluster, under cold stress conditions (≤16°C). The iron binding in Fdx is characterized by a unique absorption peak at 320 nm based on UV-visible spectroscopy. In addition, the iron-binding form of Fdx could be converted to the [2Fe-2S] cluster-bound form after transferring cold-stressed cells to normal cultivation temperatures above 25°C. In vitro experiments also revealed that Fdx could utilize bound iron to assemble the [2Fe-2S] cluster by itself. Furthermore, inactivation of the genes encoding IscS, IscU, and IscA did not limit [2Fe-2S] cluster assembly in Fdx, which was also observed by inactivating the isc or suf operon, indicating that iron-sulfur cluster biogenesis in Fdx arose from a unique pathway in E. coli . Our results suggest that the intracellular assembly of [2Fe-2S] clusters in Fdx is susceptible to environmental temperatures. The iron binding form of Fdx (Fe-Fdx) is a precursor during its maturation to a cluster binding form ([2Fe-2S] -Fdx), and reassembly of the [2Fe-2S] clusters during temperature increases is not strictly reliant on other specific iron donors and scaffold proteins within the Isc or Suf system. IMPORTANCE Fdx is an electron carrier that is required for the maturation of many other iron-sulfur proteins. Its function strictly depends on its [2Fe-2S] center that bonds with the cysteinyl S atoms of four cysteine residues within Fdx. However, the assembly mechanism of the [2Fe-2S] clusters in Fdx remains controversial. This study reports that Fdx fails to form its [2Fe-2S] cluster under cold stress conditions but instead binds a single Fe atom at the cluster binding site. Moreover, when temperatures increase, Fdx can assemble clusters by itself from its iron-only binding form in E. coli cells. The possibility remains that Fdx can effectively accept clusters from multiple sources. Nevertheless, our results suggest that Fdx has a strong iron binding activity that contributes to the assembly of its own [2Fe-2S] cluster and that Fdx acts as a temperature sensor to regulate Isc system-mediated iron-sulfur cluster biogenesis.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.03153-20
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Zinc Toxicity and Iron-Sulfur Cluster Biogenesis in Escherichia coli
    American Society for Microbiology ; 2019
    In:  Applied and Environmental Microbiology Vol. 85, No. 9 ( 2019-05)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 85, No. 9 ( 2019-05)
    Abstract: While zinc is an essential trace metal in biology, excess zinc is toxic to organisms. Previous studies have shown that zinc toxicity is associated with disruption of the [4Fe-4S] clusters in various dehydratases in Escherichia coli . Here, we report that the intracellular zinc overload in E. coli cells inhibits iron-sulfur cluster biogenesis without affecting the preassembled iron-sulfur clusters in proteins. Among the housekeeping iron-sulfur cluster assembly proteins encoded by the gene cluster iscSUA-hscBA-fdx-iscX in E. coli cells, the scaffold IscU, the iron chaperone IscA, and ferredoxin have strong zinc binding activity in cells, suggesting that intracellular zinc overload inhibits iron-sulfur cluster biogenesis by binding to the iron-sulfur cluster assembly proteins. Mutations of the conserved cysteine residues to serine in IscA, IscU, or ferredoxin completely abolish the zinc binding activity of the proteins, indicating that zinc can compete with iron or iron-sulfur cluster binding in IscA, IscU, and ferredoxin and block iron-sulfur cluster biogenesis. Furthermore, intracellular zinc overload appears to emulate the slow-growth phenotype of the E. coli mutant cells with deletion of the iron-sulfur cluster assembly proteins IscU, IscA, and ferredoxin. Our results suggest that intracellular zinc overload inhibits iron-sulfur cluster biogenesis by targeting the iron-sulfur cluster assembly proteins IscU, IscA, and ferredoxin in E. coli cells. IMPORTANCE Zinc toxicity has been implicated in causing various human diseases. High concentrations of zinc can also inhibit bacterial cell growth. However, the underlying mechanism has not been fully understood. Here, we report that zinc overload in Escherichia coli cells inhibits iron-sulfur cluster biogenesis by targeting specific iron-sulfur cluster assembly proteins. Because iron-sulfur proteins are involved in diverse physiological processes, the zinc-mediated inhibition of iron-sulfur cluster biogenesis could be largely responsible for the zinc-mediated cytotoxicity. Our finding provides new insights on how intracellular zinc overload may inhibit cellular functions in bacteria.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01967-18
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
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