Unique hexameric structure of copper-containing nitrite reductase of an anammox bacterium KSU-1.

Anaerobic ammonium oxidation (anammox) and denitrification are two different microbial reactions that form nitrogen gas. The initial step in the anammox reaction-reduction of nitrite to nitric oxide-is thought to be catalyzed by homologs of dissimilatory nitrite reductase, which is known to be involved in denitrification. Here, we reveal the crystal structure of the copper-containing nitrite reductase (CuNIR) of strain KSU-1, an anammox bacterium.

Anammox Organism KSU-1 Expresses a Novel His/DOPA Ligated Cytochrome c.

Anammox is a bacterial energy metabolic process that forms N gas from nitrite and ammonium ions. The enzymatic mechanisms of anammox have been gradually revealed; however, the electron transport chain in anammox bacteria remains poorly understood. In the present study, we purified and characterized two low-molecular-weight c-type cytochromes from an enriched culture of the anammox bacterium strain, KSU-1.