Bacterial cytochrome (Cyt)

Bacterial cytochromes are a diverse group of heme-containing proteins essential for the respiratory electron transport chain in bacteria. They function as oxidoreductases, facilitating electron transfer from substrates like quinols to terminal acceptors such as oxygen, which drives the generation of a proton motive force for ATP synthesis. In many pathogens, including Mycobacterium tuberculosis, the respiratory chain utilizes two primary terminal oxidases: the cytochrome bc1-aa3 supercomplex and the cytochrome bd oxidase. These enzymes are critical for bacterial adaptation to environmental stressors, such as hypoxia and host-derived oxidative or nitrosative stress. Because certain bacterial cytochromes, particularly the bd-type, are absent in humans or structurally distinct from human mitochondrial counterparts, they are highly attractive targets for selective antimicrobial therapy. Drugs like telacebec (Q203) specifically inhibit the bc1 complex, while inhibitors of the bd oxidase are being developed to overcome functional redundancy and achieve bactericidal effects. Additionally, bacterial cytochrome P450 enzymes are targets for azole-based drugs, further highlighting the therapeutic importance of this protein class. Overall, targeting bacterial cytochromes disrupts cellular energy production and stress resistance, making them vital components in the development of next-generation antibiotics.

Other names

Bacterial respiratory cytochromesCytochrome bd oxidaseCytochrome bc1 complexCytochrome c oxidaseQcrBCydABBacterial cytochrome P450

Inhibition of the bacterial respiratory electron transport chain by blocking quinol oxidation or oxygen reduction, leading to ATP depletion and bacterial cell death.