He et al. (2025) Nature

Nitrous oxide (N(2)O), a driver of global warming and climate change, has reached unprecedented concentrations in Earth’s atmosphere(1). Current N(2)O sources outpace N(2)O sinks, emphasizing the need for comprehensive understanding of processes that consume N(2)O. Microbes that express the enzyme N(2)O reductase (N(2)OR) convert N(2)O to climate change-neutral dinitrogen (N(2)). Known N(2)ORs belong to the canonical clade I and clade II NosZ reductases and are considered key enzymes for N(2)O reduction(2-4). Here we report a previously unrecognized protein family with a role in N(2)O reduction, clade III lactonase-type N(2)OR (L-N(2)OR), which diverges in sequence from canonical NosZ but conserves three-dimensional protein structural features. Integrated physiological, metagenomic, proteomic and structural modelling studies demonstrate that L-N(2)ORs catalyse N(2)O reduction. L-N(2)OR genes occur in several phyla, predominantly in uncultured taxa with broad geographic distribution. Our findings expand the known diversity of N(2)ORs and implicate previously unrecognized taxa (for example, Nitrospinota) in N(2)O consumption. The expansion of N(2)OR diversity and the identification of a novel type of catalyst for N(2)O reduction advances the understanding of N(2)O sinks, has implications for greenhouse gas emission and climate change modelling, and expands opportunities for innovative biotechnologies aimed at curbing N(2)O emissions(5,6).

He G, Wang W, Chen G, Xie Y, Parks JM, Davin ME, Hettich RL, Konstantinidis KT, Loffler FE. (2025) A Novel Bacterial Protein Family That Catalyses Nitrous Oxide Reduction. Nature. DOI:10.1038/s41586-025-09401-4