c-Type cytochrome-dependent formation of U(IV) nanoparticles by Shewanella oneidensis
| Autor: | Daad A. Saffarini, John M. Zachara, Matthew J. Marshall, Alexander S. Beliaev, Jeffrey S. McLean, David W. Kennedy, Barry Lai, Samantha B. Reed, Alice Dohnalkova, Vanessa L. Bailey, Margaret F. Romine, Maxim I. Boyanov, David E. Culley, Cody J. Simonson, James K. Fredrickson, Kenneth M. Kemner, Zheming Wang, Liang Shi |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2006 |
| Předmět: |
Shewanella
Cytochrome QH301-705.5 Iron Mineralogy chemistry.chemical_element Metal Nanoparticles Cytochrome c Group Glycocalyx Redox Microbiology General Biochemistry Genetics and Molecular Biology Metal Uraninite Bioremediation Extracellular polymeric substance Tissue Distribution Shewanella oneidensis Biology (General) chemistry.chemical_classification General Immunology and Microbiology biology General Neuroscience Polysaccharides Bacterial Phosphorus Periplasmic space Electron acceptor Uranium biology.organism_classification Uranium Compounds Eubacteria Biodegradation Environmental Membrane chemistry Environmental chemistry visual_art Synopsis biology.protein visual_art.visual_art_medium Environmental science General Agricultural and Biological Sciences Bacterial outer membrane Oxidation-Reduction Bacterial Outer Membrane Proteins Nuclear chemistry Research Article |
| Zdroj: | PLoS Biology, Vol 4, Iss 9, p e268 (2006) PLoS Biology PLoS Biology, Vol 4, Iss 8, p e282 (2006) |
| ISSN: | 1545-7885 1544-9173 |
| Popis: | Modern approaches for bioremediation of radionuclide contaminated environments are based on the ability of microorganisms to effectively catalyze changes in the oxidation states of metals that in turn influence their solubility. Although microbial metal reduction has been identified as an effective means for immobilizing highly-soluble uranium(VI) complexes in situ, the biomolecular mechanisms of U(VI) reduction are not well understood. Here, we show that c-type cytochromes of a dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1, are essential for the reduction of U(VI) and formation of extracelluar UO 2 nanoparticles. In particular, the outer membrane (OM) decaheme cytochrome MtrC (metal reduction), previously implicated in Mn(IV) and Fe(III) reduction, directly transferred electrons to U(VI). Additionally, deletions of mtrC and/or omcA significantly affected the in vivo U(VI) reduction rate relative to wild-type MR-1. Similar to the wild-type, the mutants accumulated UO 2 nanoparticles extracellularly to high densities in association with an extracellular polymeric substance (EPS). In wild-type cells, this UO 2-EPS matrix exhibited glycocalyx-like properties and contained multiple elements of the OM, polysaccharide, and heme-containing proteins. Using a novel combination of methods including synchrotron-based X-ray fluorescence microscopy and high-resolution immune-electron microscopy, we demonstrate a close association of the extracellular UO 2 nanoparticles with MtrC and OmcA (outer membrane cytochrome). This is the first study to our knowledge to directly localize the OM-associated cytochromes with EPS, which contains biogenic UO 2 nanoparticles. In the environment, such association of UO 2 nanoparticles with biopolymers may exert a strong influence on subsequent behavior including susceptibility to oxidation by O 2 or transport in soils and sediments. Microorganisms that catalyze changes in oxidation states of metals can be used to decontaminate environments of radionuclides. Here, c-type cytochromes on the outer membrane of a dissimilatory metal reducing bacterium are shown to be essential for the reduction of uranium(VI). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|