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A new family of proteins for energy metabolism

Researchers identify a new NADH dehydrogenase in anaerobic bacteria

Oeiras, 19.02.2015

Energy metabolism is a key feature of living organisms, but different organisms use different strategies to meet their energy requirements. Researchers from the Bacterial Energy Metabolism Lab at ITQB have identified a new family of NADH dehydrogenases (key proteins in the energy metabolism of any organism), which is widespread among anaerobic bacteria, pointing for a general and important role in their bioenergetics. The findings are now published in the journal Environmental Microbiology.

By comparing the genomes of several bacteria, researchers realized that the genes for the new NADH dehydrogenase, named FlxABCD (for flavin oxidoreductase) are always clustered with those for another enzyme called HdrABC (for heterodisulfide reductase). In fact, both genes were found to be part of the same transcriptional unit.

Analysis of the Flx-Hdr proteins also indicated that they likely operate through the new mechanism of flavin-based electron bifurcation (FBEB). This is a recently recognized, important process in the energy metabolism of anaerobic organisms that live on low levels of energy, allowing for the coupling of unfavourable to favourable reactions.

The team investigated the physiological function of the Flx-Hdr proteins using the model organism Desulfovibrio vulgaris Hildenborough, and found that they are involved in recycling NADH/NAD+, and are both essential for the oxidation of ethanol in respiratory conditions, and required for its production in fermentative conditions.

This work was awarded with a Best Poster Prize at the 18th European BioEnergetics Conference (EBEC) that took place in Lisbon last July.


Original Article

Environmental Microbiology, Early View, DOI: 10.1111/1462-2920.12689

The FlxABCD-HdrABC proteins correspond to a novel NADH dehydrogenase/heterodisulfide reductase widespread in anaerobic bacteria and involved in ethanol metabolism in Desulfovibrio vulgaris Hildenborough.

Ana Raquel Ramos, Fabian Grein, Gonçalo P Oliveira, Sofia S Venceslau, Kimberley L Keller, Judy D Wall and Inês AC Pereira


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