Preparations of Terminal Oxidase Cytochrome bd-II Isolated from Escherichia coli Reveal Significant Hydrogen Peroxide Scavenging Activity

• Published in: Biochemistry (Moscow) Vol. 87; no. 8; pp. 720 - 730
• Main Authors: Forte, Elena, Nastasi, Martina R., Borisov, Vitaliy B.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.08.2022; Springer; Springer Nature B.V
• Subjects: Bacterial physiology; Binding sites; Biochemistry; Biomedical and Life Sciences; Biomedicine; Bioorganic Chemistry; Cyanides; Cytochrome; Cytochrome bd; Cytochromes; Diatomic gases; Dithiothreitol; E coli; Electron transport; Enzymes; Escherichia coli; Ethylenediaminetetraacetic acid; Heavy metals; Heme; Hydrogen peroxide; Life Sciences; Microbiology; N-Ethylmaleimide; Oxidase; Oxidases; Oxygen; Physiological aspects; Protein binding; Reductases; Scavenging; Terminal oxidase; Transition metals; Ubiquinone; United Kingdom; Russia; cytochrome; terminal oxidase; heme; respiratory chain; reactive oxygen species
• ISSN: 0006-2979; 1608-3040
• DOI: 10.1134/S0006297922080041

Cytochrome bd -II is one of the three terminal quinol oxidases of the aerobic respiratory chain of Escherichia coli . Preparations of the detergent-solubilized untagged bd -II oxidase isolated from the bacterium were shown to scavenge hydrogen peroxide (H 2 O 2 ) with high rate producing molecular oxygen (O 2 ). Addition of H 2 O 2 to the same buffer that does not contain enzyme or contains thermally denatured cytochrome bd -II does not lead to any O 2 production. The latter observation rules out involvement of adventitious transition metals bound to the protein. The H 2 O 2 -induced O 2 production is not susceptible to inhibition by N -ethylmaleimide (the sulfhydryl binding compound), antimycin A (the compound that binds specifically to a quinol binding site), and CO (diatomic gas that binds specifically to the reduced heme d ). However, O 2 formation is inhibited by cyanide ( IC 50 = 4.5 ± 0.5 µM) and azide. Addition of H 2 O 2 in the presence of dithiothreitol and ubiquinone-1 does not inactivate cytochrome bd -II and apparently does not affect the O 2 reductase activity of the enzyme. The ability of cytochrome bd -II to detoxify H 2 O 2 could play a role in bacterial physiology by conferring resistance to the peroxide-mediated stress.