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Open Access Research article

Metabolic flexibility revealed in the genome of the cyst-forming α-1 proteobacterium Rhodospirillum centenum

Yih-Kuang Lu1, Jeremiah Marden2, Mira Han2, Wesley D Swingley3, Stephen D Mastrian4, Sugata Roy Chowdhury2, Jicheng Hao4, Tamer Helmy1, Sun Kim2, Ahmet A Kurdoglu4, Heather J Matthies5, David Rollo2, Paul Stothard6, Robert E Blankenship5, Carl E Bauer2 and Jeffrey W Touchman1*

Author Affiliations

1 School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA

2 Indiana University, Bloomington, IN 47405, USA

3 School of Natural Sciences, University of California - Merced, Merced, CA 95343, USA

4 Translational Genomics Research Institute, Phoenix, AZ 85004, USA

5 Washington University in St. Louis, St. Louis, MO 63130, USA

6 University of Alberta, Edmonton, AB T6G 2P5, Canada

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BMC Genomics 2010, 11:325  doi:10.1186/1471-2164-11-325

Published: 25 May 2010

Abstract

Background

Rhodospirillum centenum is a photosynthetic non-sulfur purple bacterium that favors growth in an anoxygenic, photosynthetic N2-fixing environment. It is emerging as a genetically amenable model organism for molecular genetic analysis of cyst formation, photosynthesis, phototaxis, and cellular development. Here, we present an analysis of the genome of this bacterium.

Results

R. centenum contains a singular circular chromosome of 4,355,548 base pairs in size harboring 4,105 genes. It has an intact Calvin cycle with two forms of Rubisco, as well as a gene encoding phosphoenolpyruvate carboxylase (PEPC) for mixotrophic CO2 fixation. This dual carbon-fixation system may be required for regulating internal carbon flux to facilitate bacterial nitrogen assimilation. Enzymatic reactions associated with arsenate and mercuric detoxification are rare or unique compared to other purple bacteria. Among numerous newly identified signal transduction proteins, of particular interest is a putative bacteriophytochrome that is phylogenetically distinct from a previously characterized R. centenum phytochrome, Ppr. Genes encoding proteins involved in chemotaxis as well as a sophisticated dual flagellar system have also been mapped.

Conclusions

Remarkable metabolic versatility and a superior capability for photoautotrophic carbon assimilation is evident in R. centenum.