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Christoph Müller

Christoph Müller

The role of the ABC transporter Nos(D)FY in nitrous oxide reductase maturation
Principal investigator: Prof. Dr. Oliver Einsle

Institute for Biochemistry
Albertstr. 21
79104 Freiburg

Phone: +49 (0) 761 203 67804


The metalloenzyme nitrous oxide reductase (N2OR) is present in the periplasm of denitrifying bacteria and catalyzes the reduction of nitrous oxide (N2O) to dinitrogen (N2) as the final step in bacterial denitrification. This reaction is of environmental importance, as atmospheric N2O acts as a greenhouse gas by absorbing the sunlight reflected from the Earth’s surface. N2OR comprises two Cu centers, the binuclear CuA and the unique, tetranuclear [4Cu:2S] cluster CuZ, making the enzyme highly sensitive to dioxygen[1]. Part of the nos gene cluster that encodes for N2OR and several accessory proteins are also the three genes, nosDFY, that encode for the ATP binding cassette (ABC) transporter Nos(D)FY[2]. This transporter is necessary for assembling a functional N2OR and seems to be involved in the biogenesis of CuZ. One hypothesis is that NosFY translocates an activated sulfide species to the periplasm, where sulfur is subsequently incorporated into the CuZ center[3]. Aim of this project is to get new insights into the maturation of N2O reductase by structural and functional characterization of the Nos(D)FY transporter.



X-ray crystallography, membrane protein purification, liposome preparation, transport assays, electron microscopy, enzyme kinetics



[1] Pomowski, A., W.G. Zumft, P.M. Kroneck, and O. Einsle. (2011). "N2O binding at a [4Cu: 2S] copper-sulphur cluster in nitrous oxide reductase." Nature, 477(7363): p. 234-237.

[2] Honisch, U. and W.G. Zumft. (2003). "Operon structure and regulation of the nos gene region of Pseudomonas stutzeri, encoding an ABC-type ATPase for maturation of nitrous oxide reductase." Journal of bacteriology, 185(6): p. 1895-1902.

[3] Wunsch, P., M. Herb, H. Wieland, U.M. Schiek, and W.G. Zumft. (2003). "Requirements for CuA and Cu-S center assembly of nitrous oxide reductase deduced from complete periplasmic enzyme maturation in the nondenitrifier Pseudomonas putida." Journal of bacteriology, 185(3): p. 887-896.