Hein, Sascha ; Simon, Jörg (2019)
Bacterial nitrous oxide respiration: electron transport chains and copper transfer reactions.
In: Advances in microbial physiology, 75
doi: 10.1016/bs.ampbs.2019.07.001
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

Biologically catalyzed nitrous oxide (NO, laughing gas) reduction to dinitrogen gas (N) is a desirable process in the light of ever-increasing atmospheric concentrations of this important greenhouse gas and ozone depleting substance. A diverse range of bacterial species produce the copper cluster-containing enzyme NO reductase (NosZ), which is the only known enzyme that converts NO to N. Based on phylogenetic analyses, NosZ enzymes have been classified into clade I or clade II and it has turned out that this differentiation is also applicable to nos gene clusters (NGCs) and some physiological traits of the corresponding microbial cells. The NosZ enzyme is the terminal reductase of anaerobic NO respiration, in which electrons derived from a donor substrate are transferred to NosZ by means of an electron transport chain (ETC) that conserves energy through proton motive force generation. This chapter presents models of the ETCs involved in clade I and clade II NO respiration as well as of the respective NosZ maturation and maintenance processes. Despite differences in NGCs and growth yields of NO-respiring microorganisms, the deduced bioenergetic framework in clade I and clade II NO respiration is assumed to be equivalent. In both cases proton motive quinol oxidation by NO is thought to be catalyzed by the Q cycle mechanism of a membrane-bound Rieske/cytochrome bc complex. However, clade I and clade II organisms are expected to differ significantly in terms of auxiliary electron transport processes as well as NosZ active site maintenance and repair.

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