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Functional Characterization of the FoxE Iron Oxidoreductase from the Photoferrotroph Rhodobacter ferrooxidans SW2

Saraiva, Ivo H. and Newman, Dianne K. and Louro, Ricardo O. (2012) Functional Characterization of the FoxE Iron Oxidoreductase from the Photoferrotroph Rhodobacter ferrooxidans SW2. Journal of Biological Chemistry, 287 (30). pp. 25541-25548. ISSN 0021-9258. PMCID PMC3408196. http://resolver.caltech.edu/CaltechAUTHORS:20120827-113105549

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Abstract

Photoferrotrophy is presumed to be an ancient type of photosynthetic metabolism in which bacteria use the reducing power of ferrous iron to drive carbon fixation. In this work the putative iron oxidoreductase of the photoferrotroph Rhodobacter ferrooxidans SW2 was cloned, purified, and characterized for the first time. This protein, FoxE, was characterized using spectroscopic, thermodynamic, and kinetic techniques. It is a c-type cytochrome that forms a trimer or tetramer in solution; the two hemes of each monomer are hexacoordinated by histidine and methionine. The hemes have positive reduction potentials that allow downhill electron transfer from many geochemically relevant ferrous iron forms to the photosynthetic reaction center. The reduction potentials of the hemes are different and are cross-assigned to fast and slow kinetic phases of ferrous iron oxidation in vitro. Lower reactivity was observed at high pH and may contribute to prevent ferric iron precipitation inside or at the surface of the cell. These results help fill in the molecular details of a metabolic process that likely contributed to the deposition of precambrian banded iron formations, globally important sedimentary rocks that are found on every continent today.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1074/jbc.M112.360636DOIArticle
http://www.jbc.org/content/287/30/25541PublisherArticle
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408196/PubMed CentralArticle
ORCID:
AuthorORCID
Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2012 The American Society for Biochemistry and Molecular Biology, Inc. Received for publication March 9, 2012; in revised form May 18, 2012; Published JBC Papers in Press June 1, 2012. This research was supported by the MIT-Portugal Program (MIT-Pt/BS-BB/0014/2008) and Fundação para a Ciência e a Tecnologia (REEQ/336/BIO/2005, PEst-OE/EQB/LA0004/2011). Recipient of Fundação para a Ciência e a Tecnologia Grant SFRH/BD/36582/2007. An Investigator of the Howard Hughes Medical Institute. We thank Catarina M. Paquete for helpful discussions and Miguel Teixeira and Manuela Pereira for support in the EPR data collection. We acknowledge CERMAX at ITQB and Rede Nacional de RMN for access to the facilities where NMR data were collected. Mass spectrometry data were obtained by the Mass Spectrometry Laboratory, Analytical Services Unit, Instituto de Tecnologia Química e Biológica. Rede Nacional deRMN(REDE/1517/RMN/2005) was supported by POCI 2010 and Fundação para a Ciência e a Tecnologia (Fundação para a Ciência e a Tecnologia).
Funders:
Funding AgencyGrant Number
MIT-Portugal ProgramMIT-Pt/BS-BB/0014/2008
Fundação para a Ciência e a Tecnologia (FCT)REEQ/336/BIO/2005
Fundação para a Ciência e a Tecnologia (FCT)PEst-OE/EQB/LA0004/2011
Fundação para a Ciência e a Tecnologia (FCT)SFRH/BD/36582/2007
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Subject Keywords:Cytochromes; Electron Transfer; Enzyme Kinetics; Metalloproteins; Photosynthesis; Rhodobacter; Photoferrotrophy
PubMed Central ID:PMC3408196
Record Number:CaltechAUTHORS:20120827-113105549
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120827-113105549
Official Citation:Ivo H. Saraiva, Dianne K. Newman, and Ricardo O. Louro Functional Characterization of the FoxE Iron Oxidoreductase from the Photoferrotroph Rhodobacter ferrooxidans SW2 J. Biol. Chem. 2012 287: 25541-25548. First Published on June 1, 2012, doi:10.1074/jbc.M112.360636
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33562
Collection:CaltechAUTHORS
Deposited By: Aucoeur Ngo
Deposited On:27 Aug 2012 21:18
Last Modified:24 Oct 2017 16:16

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