The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster.
The arsenite oxidase (Aio) from the facultative autotrophic Alphaproteobacterium Rhizobium sp. NT-26 is a bioenergetic enzyme involved in the oxidation of arsenite to arsenate. The enzyme from the distantly related heterotroph, Alcaligenes faecalis, which is thought to oxidise arsenite for detoxific...
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2013-01-01
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| Online Access: | https://doi.org/10.1371/journal.pone.0072535 |
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| author | Thomas P Warelow Muse Oke Barbara Schoepp-Cothenet Jan U Dahl Nicole Bruselat Ganesh N Sivalingam Silke Leimkühler Konstantinos Thalassinos Ulrike Kappler James H Naismith Joanne M Santini |
| author_facet | Thomas P Warelow Muse Oke Barbara Schoepp-Cothenet Jan U Dahl Nicole Bruselat Ganesh N Sivalingam Silke Leimkühler Konstantinos Thalassinos Ulrike Kappler James H Naismith Joanne M Santini |
| author_sort | Thomas P Warelow |
| collection | DOAJ |
| description | The arsenite oxidase (Aio) from the facultative autotrophic Alphaproteobacterium Rhizobium sp. NT-26 is a bioenergetic enzyme involved in the oxidation of arsenite to arsenate. The enzyme from the distantly related heterotroph, Alcaligenes faecalis, which is thought to oxidise arsenite for detoxification, consists of a large α subunit (AioA) with bis-molybdopterin guanine dinucleotide at its active site and a 3Fe-4S cluster, and a small β subunit (AioB) which contains a Rieske 2Fe-2S cluster. The successful heterologous expression of the NT-26 Aio in Escherichia coli has resulted in the solution of its crystal structure. The NT-26 Aio, a heterotetramer, shares high overall similarity to the heterodimeric arsenite oxidase from A. faecalis but there are striking differences in the structure surrounding the Rieske 2Fe-2S cluster which we demonstrate explains the difference in the observed redox potentials (+225 mV vs. +130/160 mV, respectively). A combination of site-directed mutagenesis and electron paramagnetic resonance was used to explore the differences observed in the structure and redox properties of the Rieske cluster. In the NT-26 AioB the substitution of a serine (S126 in NT-26) for a threonine as in the A. faecalis AioB explains a -20 mV decrease in redox potential. The disulphide bridge in the A. faecalis AioB which is conserved in other betaproteobacterial AioB subunits and the Rieske subunit of the cytochrome bc 1 complex is absent in the NT-26 AioB subunit. The introduction of a disulphide bridge had no effect on Aio activity or protein stability but resulted in a decrease in the redox potential of the cluster. These results are in conflict with previous data on the betaproteobacterial AioB subunit and the Rieske of the bc 1 complex where removal of the disulphide bridge had no effect on the redox potential of the former but a decrease in cluster stability was observed in the latter. |
| format | Article |
| id | doaj-art-080c252a643540bda2f9abc0330de010 |
| institution | OA Journals |
| issn | 1932-6203 |
| language | English |
| publishDate | 2013-01-01 |
| publisher | Public Library of Science (PLoS) |
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| spelling | doaj-art-080c252a643540bda2f9abc0330de0102025-08-20T02:22:45ZengPublic Library of Science (PLoS)PLoS ONE1932-62032013-01-0188e7253510.1371/journal.pone.0072535The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster.Thomas P WarelowMuse OkeBarbara Schoepp-CothenetJan U DahlNicole BruselatGanesh N SivalingamSilke LeimkühlerKonstantinos ThalassinosUlrike KapplerJames H NaismithJoanne M SantiniThe arsenite oxidase (Aio) from the facultative autotrophic Alphaproteobacterium Rhizobium sp. NT-26 is a bioenergetic enzyme involved in the oxidation of arsenite to arsenate. The enzyme from the distantly related heterotroph, Alcaligenes faecalis, which is thought to oxidise arsenite for detoxification, consists of a large α subunit (AioA) with bis-molybdopterin guanine dinucleotide at its active site and a 3Fe-4S cluster, and a small β subunit (AioB) which contains a Rieske 2Fe-2S cluster. The successful heterologous expression of the NT-26 Aio in Escherichia coli has resulted in the solution of its crystal structure. The NT-26 Aio, a heterotetramer, shares high overall similarity to the heterodimeric arsenite oxidase from A. faecalis but there are striking differences in the structure surrounding the Rieske 2Fe-2S cluster which we demonstrate explains the difference in the observed redox potentials (+225 mV vs. +130/160 mV, respectively). A combination of site-directed mutagenesis and electron paramagnetic resonance was used to explore the differences observed in the structure and redox properties of the Rieske cluster. In the NT-26 AioB the substitution of a serine (S126 in NT-26) for a threonine as in the A. faecalis AioB explains a -20 mV decrease in redox potential. The disulphide bridge in the A. faecalis AioB which is conserved in other betaproteobacterial AioB subunits and the Rieske subunit of the cytochrome bc 1 complex is absent in the NT-26 AioB subunit. The introduction of a disulphide bridge had no effect on Aio activity or protein stability but resulted in a decrease in the redox potential of the cluster. These results are in conflict with previous data on the betaproteobacterial AioB subunit and the Rieske of the bc 1 complex where removal of the disulphide bridge had no effect on the redox potential of the former but a decrease in cluster stability was observed in the latter.https://doi.org/10.1371/journal.pone.0072535 |
| spellingShingle | Thomas P Warelow Muse Oke Barbara Schoepp-Cothenet Jan U Dahl Nicole Bruselat Ganesh N Sivalingam Silke Leimkühler Konstantinos Thalassinos Ulrike Kappler James H Naismith Joanne M Santini The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster. PLoS ONE |
| title | The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster. |
| title_full | The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster. |
| title_fullStr | The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster. |
| title_full_unstemmed | The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster. |
| title_short | The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster. |
| title_sort | respiratory arsenite oxidase structure and the role of residues surrounding the rieske cluster |
| url | https://doi.org/10.1371/journal.pone.0072535 |
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