New insights into synthesis and function of heme c proteins of anammox bacteria

Contains fulltext : 179020.pdf (publisher's version ) (Open Access)Radboud University, 19 december 2017Promotor : Jetten, M.S.M. Co-promotores : Kartal, B, Reimann, J.192 p

Identification of the type ii cytochrome c maturation pathway in anammox bacteria by comparative genomics

Contains fulltext : 123439.pdf (publisher's version ) (Open Access

A 60-heme reductase complex from an anammox bacterium shows an extended electron transfer pathway

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Characterization of a nitrite-reducing octaheme hydroxylamine oxidoreductase that lacks the tyrosine cross-link

Contains fulltext : 236764.pdf (Publisher’s version ) (Open Access

Membrane-bound electron transport systems of an anammox bacterium: A complexome analysis

Contains fulltext : 161820.pdf (publisher's version ) (Closed access

Structural insights into biological hydrazine synthesis

Contains fulltext : 163338.pdf (publisher's version ) (Open Access

A 192-heme electron transfer network in the hydrazine dehydrogenase complex

Anaerobic ammonium oxidation (anammox) is a major process in the biogeochemical nitrogen cycle in which nitrite and ammonium are converted to dinitrogen gas and water through the highly reactive intermediate hydrazine. So far, it is unknown how anammox organisms convert the toxic hydrazine into nitrogen and harvest the extremely low potential electrons (-750 mV) released in this process. We report the crystal structure and cryo electron microscopy structures of the responsible enzyme, hydrazine dehydrogenase, which is a 1.7 MDa multiprotein complex containing an extended electron transfer network of 192 heme groups spanning the entire complex. This unique molecular arrangement suggests a way in which the protein stores and releases the electrons obtained from hydrazine conversion, the final step in the globally important anammox process

Immunogold localization of key metabolic enzymes in the anammoxosome and on the tubule-like structures of Kuenenia stuttgartiensis

Anaerobic ammonium-oxidizing (anammox) bacteria oxidize ammonium with nitrite as the terminal electron acceptor to form dinitrogen gas in the absence of oxygen. Anammox bacteria have a compartmentalized cell plan with a central membrane-bound “prokaryotic organelle” called the anammoxosome. The anammoxosome occupies most of the cell volume, has a curved membrane, and contains conspicuous tubule-like structures of unknown identity and function. It was suggested previously that the catalytic reactions of the anammox pathway occur in the anammoxosome, and that proton motive force was established across its membrane. Here, we used antibodies raised against five key enzymes of the anammox catabolism to determine their cellular location. The antibodies were raised against purified native hydroxylamine oxidoreductase-like protein kustc0458 with its redox partner kustc0457, hydrazine dehydrogenase (HDH; kustc0694), hydroxylamine oxidase (HOX; kustc1061), nitrite oxidoreductase (NXR; kustd1700/03/04), and hydrazine synthase (HZS; kuste2859-61) of the anammox bacterium Kuenenia stuttgartiensis. We determined that all five protein complexes were exclusively located inside the anammoxosome matrix. Four of the protein complexes did not appear to form higher-order protein organizations. However, the present data indicated for the first time that NXR is part of the tubule-like structures, which may stretch the whole length of the anammoxosome. These findings support the anammoxosome as the locus of catabolic reactions of the anammox pathway.BT/BiotechnologyApplied Science