Functional design of bacterial superoxide:quinone oxidoreductase.

Abou Hamdan, Abbas; Mahler, Roman; Grossenbacher, Philipp; Biner, Olivier; Sjöstrand, Dan; Lochner, Martin; Högbom, Martin; von Ballmoos, Christoph (2022). Functional design of bacterial superoxide:quinone oxidoreductase. Biochimica et biophysica acta. Bioenergetics, 1863(7), p. 148583. Elsevier 10.1016/j.bbabio.2022.148583

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The superoxide anion - molecular oxygen reduced by a single electron - is produced in large amounts by enzymatic and adventitious reactions. It can perform a range of cellular functions, including bacterial warfare and iron uptake, signalling and host immune response in eukaryotes. However, it also serves as precursor for more deleterious species such as the hydroxyl anion or peroxynitrite and defense mechanisms to neutralize superoxide are important for cellular health. In addition to the soluble proteins superoxide dismutase and superoxide reductase, recently the membrane embedded diheme cytochrome b561 (CybB) from E. coli has been proposed to act as a superoxide:quinone oxidoreductase. Here, we confirm superoxide and cellular ubiquinones or menaquinones as natural substrates and show that quinone binding to the enzyme accelerates the reaction with superoxide. The reactivity of the substrates is in accordance with the here determined midpoint potentials of the two b hemes (+48 and -23 mV / NHE). Our data suggest that the enzyme can work near the diffusion limit in the forward direction and can also catalyse the reverse reaction efficiently under physiological conditions. The data is discussed in the context of described cytochrome b561 proteins and potential physiological roles of CybB.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Biochemistry and Molecular Medicine

Graduate School:

Graduate School for Cellular and Biomedical Sciences (GCB)

UniBE Contributor:

Abou Hamdan, Abbas Maxime, Mahler, Roman Alois, Grossenbacher, Philipp, Lochner, Martin, von Ballmoos, Christoph


500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry
600 Technology > 610 Medicine & health








Pubmed Import

Date Deposited:

08 Jun 2022 09:55

Last Modified:

06 Jun 2023 00:25

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

Cytochrome b561 Membrane protein Menaquinone Superoxide Superoxide oxidase Ubiquinone




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