ArticleThe Journal of biological chemistry
Characterization of a nitrite-reducing octaheme hydroxylamine oxidoreductase that lacks the tyrosine cross-link.
Article in The Journal of biological chemistry. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 16 papers.
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16 citing papers in PubMed, 37 citations in OpenAlex.
- Enrichment and characterization of a haloalkaline-tolerant anammox bacterium.The ISME journal · 2026Article
- Origin and Evolution of Key Enzymes in the Anammox Pathway Revisited.Genome biology and evolution · 2026Article
- Nitric oxide-forming nitrite reductases in the anaerobic ammonium oxidizer Kuenenia stuttgartiensis.FEBS open bio · 2025Article
- Cold seeps are potential hotspots of deep-sea nitrogen loss driven by microorganisms across 21 phyla.Nature communications · 2025Article
- Fractionating proteins with nitrite-reducing activity in "Frontiers in microbiology · 2025Article
- Genomic analysis of the class Phycisphaerae reveals a versatile group of complex carbon-degrading bacteria.Antonie van Leeuwenhoek · 2024Article
- "Applied and environmental microbiology · 2023Article
- Cytochrome P460 Cofactor Maturation Proceeds via Peroxide-Dependent Post-translational Modification.Journal of the American Chemical Society · 2023Article
- Novel and unusual genes for nitrogen and metal cycling in Planctomycetota- and KSB1-affiliated metagenome-assembled genomes reconstructed from a marine subsea tunnel.FEMS microbiology letters · 2023Article
- A New Paradigm of Multiheme Cytochrome Evolution by Grafting and Pruning Protein Modules.Molecular biology and evolution · 2022Article
- Introducing Candidatus Bathyanammoxibiaceae, a family of bacteria with the anammox potential present in both marine and terrestrial environments.ISME communications · 2022Article
- Metagenomic evidence of a novel family of anammox bacteria in a subsea environment.Environmental microbiology · 2022Article
- Metagenomic Analysis of Five Phylogenetically Distant Anammox Bacterial Enrichment Cultures.Microbes and environments · 2022Article
- NHMicrobes and environments · 2022Article
- Structural and functional characterization of the intracellular filament-forming nitrite oxidoreductase multiprotein complex.Nature microbiology · 2021Article
- Specificity of SmallACS omega · 2021Article
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8 authors at 2 institutions in 2 countries.
Funding
Abstract
The hydroxylamine oxidoreductase (HAO) family consists of octaheme proteins that harbor seven bis-His ligated electron-transferring hemes and one 5-coordinate catalytic heme with His axial ligation. Oxidative HAOs have a homotrimeric configuration with the monomers covalently attached to each other via a unique double cross-link between a Tyr residue and the catalytic heme moiety of an adjacent subunit. This cross-linked active site heme, termed the P460 cofactor, has been hypothesized to modulate enzyme reactivity toward oxidative catalysis. Conversely, the absence of this cross-link is predicted to favor reductive catalysis. However, this prediction has not been directly tested. In this study, an HAO homolog that lacks the heme-Tyr cross-link (HAOr) was purified to homogeneity from the nitrite-dependent anaerobic ammonium-oxidizing (anammox) bacterium Kuenenia stuttgartiensis, and its catalytic and spectroscopic properties were assessed. We show that HAOr reduced nitrite to nitric oxide and also reduced nitric oxide and hydroxylamine as nonphysiological substrates. In contrast, HAOr was not able to oxidize hydroxylamine or hydrazine supporting the notion that cross-link-deficient HAO enzymes are reductases. Compared with oxidative HAOs, we found that HAOr harbors an active site heme with a higher (at least 80 mV) midpoint potential and a much lower degree of porphyrin ruffling. Based on the physiology of anammox bacteria and our results, we propose that HAOr reduces nitrite to nitric oxide in vivo, providing anammox bacteria with NO, which they use to activate ammonium in the absence of oxygen.
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