Insights into an enzyme that fights a common greenhouse gas – ScienceDaily


An enzyme that breaks down the greenhouse gas nitrous oxide (N2O) could one day give scientists a powerful new tool to reduce the amount of gas in the atmosphere, thanks in part to new findings published today in Nature.

The study describes in detail how the enzyme – N2O-Reductase – is compiled and provides important insight into its ability to convert nitrous oxide into harmless nitrogen and water. The research was conducted by VAI Associate Professor Juan Du, Ph.D., VAI Associate Professor Wei Lü, Ph.D., and Professor Oliver Einsle, Ph.D. headed by the University of Freiburg.

“Tackling greenhouse gases is a massive, multi-faceted undertaking. Today’s results are an early but important step towards the development of another tool to potentially address a contribution to climate change,” Du said.

Greenhouse gases trap heat in the Earth’s atmosphere and contribute to rising global temperatures. Nitrous oxide accounts for only about 7% of the greenhouse gases produced by human activities, but its impact is 300 times that of the most common greenhouse gas, carbon dioxide. According to the US Environmental Protection Agency, nitrous oxide is most commonly produced by agricultural practices such as the use of nitrogen fertilizers. It can remain in the atmosphere for more than a century.

N2O-reductase is used by certain microbes to break down nitrogen-based molecules as part of the earth’s natural nitrogen cycle. Using nitrogen-rich fertilizers can overwhelm these microbes’ ability to completely abate nitrous oxide, allowing it to escape into the atmosphere. Understanding exactly how this happens is a crucial step towards strategies to mediate nitrous oxide and thereby reduce atmospheric concentrations.

On the biotechnological applications of N2O-reductase, it is crucial to understand and control the delivery of copper ions during the assembly of the enzyme in the cell. The study focused on the structure of a membrane protein complex called NosDFY and how it transforms N2O-reductase assembly. Using a variety of mapping and modeling techniques, the team discovered that NosDFY acts as a channel that converts chemical energy into mechanical energy, which in turn drives the supply of copper ions needed to generate more N2O reductase.

The results reshape a decades-old belief in this crucial copper delivery system and reveal novel functionality for similar molecules. Although additional research is needed, the results provide a detailed plan that can be translated into future environmental remediation strategies.

Christoph Müller and Lin Zhang from the Institute of Biochemistry at the University of Freiburg are co-first authors of the study. Other authors are Sara Zipfel, Annika Topitsch, Marleen Lutz, Johannes Eckert and Benedikt Prasser from the Institute of Biochemistry at the University of Freiburg; and Mohamed Chami from the BioEM Lab at the University of Basel. The following groups also contributed to this project: VAI’s David Van Andel Advanced Cryo-Electron Microscopy Suite, the Pacific Northwest Center for Cryo-EM, VAI’s High-Performance Computing team, and the bwHPC cluster.

The research reported in this publication was awarded by the European Research Council under award no. 310656 (Einsle); German research community under price no. SFB1381 (project ID: 403222702; Einsle) and award no. GRK2202 (Project ID: 46710898, Einsle); the BIOSS Center for Biological Signaling Studies at the Albert-Ludwigs-University Freiburg (Einsle); a McKnight Scholar Award (You); a Klingenstein-Simons Fellowship Award in Neuroscience (Du); a Sloan Research Fellowship in Neuroscience (Du); a Pew Scholars in Biomedical Research Award from the Pew Charitable Trusts (Du); and the National Institute of Neurological Disorders and Stroke of the National Institutes of Health under award no. R01NS111031 (You).

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