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Nonredundant Roles for Cytochrome c_2 and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1

Bird, Lina J. and Saralva, Ivo H. and Park, Shannon and Calçada, Eduardo O. and Salgueiro, Carlos A. and Nitschke, Wolfang and Louro, Ricardo O. and Newman, Dianne K. (2014) Nonredundant Roles for Cytochrome c_2 and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1. Journal of Bacteriology, 196 (4). pp. 850-858. ISSN 0021-9193. PMCID PMC3911180. http://resolver.caltech.edu/CaltechAUTHORS:20140407-131828981

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Abstract

The purple bacterium Rhodopseudomonas palustris TIE-1 expresses multiple small high-potential redox proteins during photoautotrophic growth, including two high-potential iron-sulfur proteins (HiPIPs) (PioC and Rpal_4085) and a cytochrome c_2. We evaluated the role of these proteins in TIE-1 through genetic, physiological, and biochemical analyses. Deleting the gene encoding cytochrome c_2 resulted in a loss of photosynthetic ability by TIE-1, indicating that this protein cannot be replaced by either HiPIP in cyclic electron flow. PioC was previously implicated in photoferrotrophy, an unusual form of photosynthesis in which reducing power is provided through ferrous iron oxidation. Using cyclic voltammetry (CV), electron paramagnetic resonance (EPR) spectroscopy, and flash-induced spectrometry, we show that PioC has a midpoint potential of 450 mV, contains all the typical features of a HiPIP, and can reduce the reaction centers of membrane suspensions in a light-dependent manner at a much lower rate than cytochrome c_2. These data support the hypothesis that PioC linearly transfers electrons from iron, while cytochrome c_2 is required for cyclic electron flow. Rpal_4085, despite having spectroscopic characteristics and a reduction potential similar to those of PioC, is unable to reduce the reaction center. Rpal_4085 is upregulated by the divalent metals Fe(II), Ni(II), and Co(II), suggesting that it might play a role in sensing or oxidizing metals in the periplasm. Taken together, our results suggest that these three small electron transfer proteins perform different functions in the cell.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1128/JB.00843-13 DOIArticle
http://jb.asm.org/content/196/4/850PublisherArticle
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3911180/PubMed CentralArticle
http://jb.asm.org/content/196/4/850/suppl/DCSupplementalPublisherSupplemental Material
ORCID:
AuthorORCID
Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2014 American Society for Microbiology. Received 2 August 2013 Accepted 28 November 2013. Published ahead of print 6 December 2013. The N-terminal data were provided by the Analytical Laboratory, Analytical Services Unit, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa. We thank Pablo Gonzales at FCT-UNL for the EPR spectra of pure HiPIPs and Miguel Teixeira at ITQB for obtaining the other EPR data and for helpful discussions. We thank J. Lavergne (Cadarache, France) for advice on kinetic experiments. We thank the Howard Hughes Medical Institute (HHMI) and the MIT-Portugal Program (MIT-Pt/BS-BB/0014/2008) for supporting this work. D.K.N. is an HHMI investigator, and L.J.B. was a PEO scholar. This work was also supported by FCT through grant PEst-OE/EQB/LA0004/2011 and grant PTDC/BIA-PRO/098158/2008. I.H.S. is the recipient of FCT grant SFRH/BD/36582/2007.
Funders:
Funding AgencyGrant Number
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
MIT-Portugal ProgramMIT-Pt/BS-BB/0014/2008
Fundação para a Ciência e a Tecnologia (FCT)PEst-OE/EQB/LA0004/2011
Fundação para a Ciência e a Tecnologia (FCT)PTDC/BIA-PRO/098158/2008
Fundação para a Ciência e a Tecnologia (FCT)SFRH/BD/36582/2007
PubMed Central ID:PMC3911180
Record Number:CaltechAUTHORS:20140407-131828981
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140407-131828981
Official Citation:Nonredundant Roles for Cytochrome c2 and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1 Lina J. Bird, Ivo H. Saraiva, Shannon Park, Eduardo O. Calçada, Carlos A. Salgueiro, Wolfgang Nitschke, Ricardo O. Louro, and Dianne K. Newman J. Bacteriol. February 2014 196:4 850-858; Accepted manuscript posted online 6 December 2013, doi:10.1128/JB.00843-13
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44703
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:07 Apr 2014 21:00
Last Modified:24 Oct 2017 16:21

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