Selenium controls transcription of paralogous formate dehydrogenase genes in the termite gut acetogen, Treponema primitia
Article first published online: 7 MAR 2010
© 2010 Society for Applied Microbiology and Blackwell Publishing Ltd
Special Issue: Symbiosis. Editors: Professors Paola Bonfante, Karen Visick, and Moriya Ohkuma
Volume 12, Issue 8, pages 2245–2258, August 2010
How to Cite
Matson, E. G., Zhang, X. and Leadbetter, J. R. (2010), Selenium controls transcription of paralogous formate dehydrogenase genes in the termite gut acetogen, Treponema primitia. Environmental Microbiology, 12: 2245–2258. doi: 10.1111/j.1462-2920.2010.02188.x
- Issue published online: 4 AUG 2010
- Article first published online: 7 MAR 2010
- Received 9 April, 2009; accepted 11 January, 2010.
The termite gut spirochete, Treponema primitia, is a CO2-reductive acetogen that is phylogenetically distinct from other distantly related and more extensively studied acetogens such as Moorella thermoacetica. Research on T. primitia has revealed details about the role of spirochetes in CO2-reductive acetogenesis, a process important to the mutualism occurring between termites and their gut microbial communities. Here, a locus of the T. primitia genome containing Wood-Ljungdahl pathway genes for CO2-reductive acetogenesis was sequenced. This locus contained methyl-branch genes of the pathway (i.e. for the reduction of CO2 to the level of methyl-tetrahydrofolate) including paralogous genes for cysteine and selenocysteine (Sec) variants of formate dehydrogenase (FDH) and genes for Sec incorporation. The FDH variants affiliated phylogenetically with hydrogenase-linked FDH enzymes, suggesting that T. primitia FDH enzymes utilize electrons derived directly from molecular H2. Sub-nanomolar concentrations of selenium decreased transcript levels of the cysteine variant FDH gene. Selenium concentration did not markedly influence the level of mRNA upstream of the Sec-codon in the Sec variant FDH; however, the level of transcript extending downstream of the Sec-codon increased incrementally with increasing selenium concentrations. The features and regulation of these FDH genes are an indication that T. primitia may experience dynamic selenium availability in its H2-rich gut environment.