Functional characterisation of the [FeFe] hydrogenase SoHydAB from Shewanella oneidensis

Hydrogenases are metalloenzymes that catalyse the interconversion between two protons and two electrons on one hand and molecular hydrogen (H2) on the other hand. Diverse members of this enzyme family fulfil a wide variety of metabolic functions. The [FeFe] hydrogenase of Shewanella oneidensis presents an intriguing case.

This bacterium is well known for its metabolic versatility, allowing it to grow on and reduce an astounding variety of substrates, including heavy metals and highly toxic chemicals. These abilities have made Shewanella a popular choice for the application in microbial fuel cells and wastewater treatment. Due to these properties, the physiology and metabolism of Shewanella has been studied intensively and is well characterised. Biochemically however, the hydrogen metabolism of Shewanella remains understudied.

The [FeFe] hydrogenase of Shewanella oneidensis is located in the periplasm, but presumably anchored to the inner membrane. Its activity is completely abolished by the deletion of formate dehydrogenase, but unlike E. coli for example, Shewanella does not appear to form a formate-hydrogen-lyase complex. Furthermore, it has been shown that hydrogenase activity is also fully abolished in the absence of menaquinone.

Taken together, the properties of this enzyme and its metabolic context suggest that it either forms a scientifically interesting complex or has a variety of interaction partners, which is likely to lead to further research questions regarding the mechanisms and regulation of these interactions. The first step in elucidating the hydrogen metabolism in Shewanella is a full investigation into the properties of the hydrogenase itself.

This poster presents the first characterisation of the [FeFe] hydrogenase SoHydAB utilising an array of chromatographic, electrochemical and spectroscopic methods.