TY  - JOUR
A1  - Moreno Chicano, Tadeo
A1  - Dietrich, Lea Theresa
A1  - Almeida, Naomi M. de
A1  - Akram, Mohd
A1  - Hartmann, Elisabeth
A1  - Leidreiter, Franziska
A1  - Leopoldus, Daniel
A1  - Mueller, Melanie
A1  - Sánchez, Ricardo
A1  - Nuijten, Guylaine H. L.
A1  - Reimann, Joachim
A1  - Seifert, Kerstin-Anikó
A1  - Schlichting, Ilme
A1  - Niftrik, Laura van
A1  - Jetten, Michael S. M.
A1  - Dietl, Andreas
A1  - Kartal, Boran
A1  - Parey, Kristian Kurt
A1  - Barends, Thomas R. M.
T1  - Structural and functional characterization of the intracellular filament-forming nitrite oxidoreductase multiprotein complex
T2  - Nature microbiology
N2  - Nitrate is an abundant nutrient and electron acceptor throughout Earth’s biosphere. Virtually all nitrate in nature is produced by the oxidation of nitrite by the nitrite oxidoreductase (NXR) multiprotein complex. NXR is a crucial enzyme in the global biological nitrogen cycle, and is found in nitrite-oxidizing bacteria (including comammox organisms), which generate the bulk of the nitrate in the environment, and in anaerobic ammonium-oxidizing (anammox) bacteria which produce half of the dinitrogen gas in our atmosphere. However, despite its central role in biology and decades of intense study, no structural information on NXR is available. Here, we present a structural and biochemical analysis of the NXR from the anammox bacterium Kuenenia stuttgartiensis, integrating X-ray crystallography, cryo-electron tomography, helical reconstruction cryo-electron microscopy, interaction and reconstitution studies and enzyme kinetics. We find that NXR catalyses both nitrite oxidation and nitrate reduction, and show that in the cell, NXR is arranged in tubules several hundred nanometres long. We reveal the tubule architecture and show that tubule formation is induced by a previously unidentified, haem-containing subunit, NXR-T. The results also reveal unexpected features in the active site of the enzyme, an unusual cofactor coordination in the protein’s electron transport chain, and elucidate the electron transfer pathways within the complex.
KW  - Cryoelectron microscopy
KW  - Cryoelectron tomography
KW  - X-ray crystallography
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/63274
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-632741
SN  - 2058-5276
N1  - Data availability

The NXR-ABC crystal structure and structure factor amplitudes were deposited in the PDB under accession code 7B04. EM maps are available from the EMDB under accession codes EMD-11860 and EMD-11861. Source data are provided with this paper. All other data are available from the authors on request.
N1  - Open access funding provided by Max Planck Institute for Medical Research.
VL  - 6
SP  - 1129
EP  - 1139
PB  - Nature Publishing Group
CY  - London
ER  -