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Importance of c-Type cytochromes for U(VI) reduction by Geobacter sulfurreducens
BACKGROUND: In order to study the mechanism of U(VI) reduction, the effect of deleting c-type cytochrome genes on the capacity of Geobacter sulfurreducens to reduce U(VI) with acetate serving as the electron donor was investigated. RESULTS: The ability of several c-type cytochrome deficient mutants...
Autores principales: | , , , , , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
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BioMed Central
2007
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1829397/ https://www.ncbi.nlm.nih.gov/pubmed/17346345 http://dx.doi.org/10.1186/1471-2180-7-16 |
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author | Shelobolina, Evgenya S Coppi, Maddalena V Korenevsky, Anton A DiDonato, Laurie N Sullivan, Sara A Konishi, Hiromi Xu, Huifang Leang, Ching Butler, Jessica E Kim, Byoung-Chan Lovley, Derek R |
author_facet | Shelobolina, Evgenya S Coppi, Maddalena V Korenevsky, Anton A DiDonato, Laurie N Sullivan, Sara A Konishi, Hiromi Xu, Huifang Leang, Ching Butler, Jessica E Kim, Byoung-Chan Lovley, Derek R |
author_sort | Shelobolina, Evgenya S |
collection | PubMed |
description | BACKGROUND: In order to study the mechanism of U(VI) reduction, the effect of deleting c-type cytochrome genes on the capacity of Geobacter sulfurreducens to reduce U(VI) with acetate serving as the electron donor was investigated. RESULTS: The ability of several c-type cytochrome deficient mutants to reduce U(VI) was lower than that of the wild type strain. Elimination of two confirmed outer membrane cytochromes and two putative outer membrane cytochromes significantly decreased (ca. 50–60%) the ability of G. sulfurreducens to reduce U(VI). Involvement in U(VI) reduction did not appear to be a general property of outer membrane cytochromes, as elimination of two other confirmed outer membrane cytochromes, OmcB and OmcC, had very little impact on U(VI) reduction. Among the periplasmic cytochromes, only MacA, proposed to transfer electrons from the inner membrane to the periplasm, appeared to play a significant role in U(VI) reduction. A subpopulation of both wild type and U(VI) reduction-impaired cells, 24–30%, accumulated amorphous uranium in the periplasm. Comparison of uranium-accumulating cells demonstrated a similar amount of periplasmic uranium accumulation in U(VI) reduction-impaired and wild type G. sulfurreducens. Assessment of the ability of the various suspensions to reduce Fe(III) revealed no correlation between the impact of cytochrome deletion on U(VI) reduction and reduction of Fe(III) hydroxide and chelated Fe(III). CONCLUSION: This study indicates that c-type cytochromes are involved in U(VI) reduction by Geobacter sulfurreducens. The data provide new evidence for extracellular uranium reduction by G. sulfurreducens but do not rule out the possibility of periplasmic uranium reduction. Occurrence of U(VI) reduction at the cell surface is supported by the significant impact of elimination of outer membrane cytochromes on U(VI) reduction and the lack of correlation between periplasmic uranium accumulation and the capacity for uranium reduction. Periplasmic uranium accumulation may reflect the ability of uranium to penetrate the outer membrane rather than the occurrence of enzymatic U(VI) reduction. Elimination of cytochromes rarely had a similar impact on both Fe(III) and U(VI) reduction, suggesting that there are differences in the routes of electron transfer to U(VI) and Fe(III). Further studies are required to clarify the pathways leading to U(VI) reduction in G. sulfurreducens. |
format | Text |
id | pubmed-1829397 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2007 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-18293972007-03-22 Importance of c-Type cytochromes for U(VI) reduction by Geobacter sulfurreducens Shelobolina, Evgenya S Coppi, Maddalena V Korenevsky, Anton A DiDonato, Laurie N Sullivan, Sara A Konishi, Hiromi Xu, Huifang Leang, Ching Butler, Jessica E Kim, Byoung-Chan Lovley, Derek R BMC Microbiol Research Article BACKGROUND: In order to study the mechanism of U(VI) reduction, the effect of deleting c-type cytochrome genes on the capacity of Geobacter sulfurreducens to reduce U(VI) with acetate serving as the electron donor was investigated. RESULTS: The ability of several c-type cytochrome deficient mutants to reduce U(VI) was lower than that of the wild type strain. Elimination of two confirmed outer membrane cytochromes and two putative outer membrane cytochromes significantly decreased (ca. 50–60%) the ability of G. sulfurreducens to reduce U(VI). Involvement in U(VI) reduction did not appear to be a general property of outer membrane cytochromes, as elimination of two other confirmed outer membrane cytochromes, OmcB and OmcC, had very little impact on U(VI) reduction. Among the periplasmic cytochromes, only MacA, proposed to transfer electrons from the inner membrane to the periplasm, appeared to play a significant role in U(VI) reduction. A subpopulation of both wild type and U(VI) reduction-impaired cells, 24–30%, accumulated amorphous uranium in the periplasm. Comparison of uranium-accumulating cells demonstrated a similar amount of periplasmic uranium accumulation in U(VI) reduction-impaired and wild type G. sulfurreducens. Assessment of the ability of the various suspensions to reduce Fe(III) revealed no correlation between the impact of cytochrome deletion on U(VI) reduction and reduction of Fe(III) hydroxide and chelated Fe(III). CONCLUSION: This study indicates that c-type cytochromes are involved in U(VI) reduction by Geobacter sulfurreducens. The data provide new evidence for extracellular uranium reduction by G. sulfurreducens but do not rule out the possibility of periplasmic uranium reduction. Occurrence of U(VI) reduction at the cell surface is supported by the significant impact of elimination of outer membrane cytochromes on U(VI) reduction and the lack of correlation between periplasmic uranium accumulation and the capacity for uranium reduction. Periplasmic uranium accumulation may reflect the ability of uranium to penetrate the outer membrane rather than the occurrence of enzymatic U(VI) reduction. Elimination of cytochromes rarely had a similar impact on both Fe(III) and U(VI) reduction, suggesting that there are differences in the routes of electron transfer to U(VI) and Fe(III). Further studies are required to clarify the pathways leading to U(VI) reduction in G. sulfurreducens. BioMed Central 2007-03-08 /pmc/articles/PMC1829397/ /pubmed/17346345 http://dx.doi.org/10.1186/1471-2180-7-16 Text en Copyright © 2007 Shelobolina et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Article Shelobolina, Evgenya S Coppi, Maddalena V Korenevsky, Anton A DiDonato, Laurie N Sullivan, Sara A Konishi, Hiromi Xu, Huifang Leang, Ching Butler, Jessica E Kim, Byoung-Chan Lovley, Derek R Importance of c-Type cytochromes for U(VI) reduction by Geobacter sulfurreducens |
title | Importance of c-Type cytochromes for U(VI) reduction by Geobacter sulfurreducens |
title_full | Importance of c-Type cytochromes for U(VI) reduction by Geobacter sulfurreducens |
title_fullStr | Importance of c-Type cytochromes for U(VI) reduction by Geobacter sulfurreducens |
title_full_unstemmed | Importance of c-Type cytochromes for U(VI) reduction by Geobacter sulfurreducens |
title_short | Importance of c-Type cytochromes for U(VI) reduction by Geobacter sulfurreducens |
title_sort | importance of c-type cytochromes for u(vi) reduction by geobacter sulfurreducens |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1829397/ https://www.ncbi.nlm.nih.gov/pubmed/17346345 http://dx.doi.org/10.1186/1471-2180-7-16 |
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