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Last update 23 Jan 2025

Cytochrome b

Last update 23 Jan 2025

Basic Info

Synonyms

COB, Complex III subunit 3, Complex III subunit III

+ [6]

Introduction

Component of the ubiquinol-cytochrome c reductase complex (complex III or cytochrome b-c1 complex) that is part of the mitochondrial respiratory chain. The b-c1 complex mediates electron transfer from ubiquinol to cytochrome c. Contributes to the generation of a proton gradient across the mitochondrial membrane that is then used for ATP synthesis.

Drugs associated with Cytochrome b

TPN-0006288

Target

QcrB

Mechanism

QcrB inhibitors

Active Org.

Infectious Disease Research Institute

Originator Org.

Infectious Disease Research Institute

Active Indication

Mycobacterium Tuberculosis, Susceptibility to Infection By

Inactive Indication-

Drug Highest PhasePreclinical

First Approval Ctry. / Loc.-

First Approval Date20 Jan 1800

TPN-0006245

Target

QcrB

Mechanism

QcrB inhibitors

Active Org.

Infectious Disease Research Institute

Originator Org.

Infectious Disease Research Institute

Active Indication

Mycobacterium Tuberculosis, Susceptibility to Infection By

Inactive Indication-

Drug Highest PhasePreclinical

First Approval Ctry. / Loc.-

First Approval Date20 Jan 1800

TPN-0006273

Target

QcrB

Mechanism

QcrB inhibitors

Active Org.

Infectious Disease Research Institute

Originator Org.

Infectious Disease Research Institute

Active Indication

Mycobacterium Tuberculosis, Susceptibility to Infection By

Inactive Indication-

Drug Highest PhasePreclinical

First Approval Ctry. / Loc.-

First Approval Date20 Jan 1800

100 Clinical Results associated with Cytochrome b

100 Translational Medicine associated with Cytochrome b

0 Patents (Medical) associated with Cytochrome b

5,521

Literatures (Medical) associated with Cytochrome b

01 Feb 2025·Journal of Biological Chemistry

Menaquinone-specific turnover by Mycobacterium tuberculosis cytochrome bd is redox regulated by the Q-loop disulfide bond

Article

Author: van der Velden, Tijn T ; Waterham, Caspar Y J ; Kayastha, Kanwal ; Brünle, Steffen ; Jeuken, Lars J C

Cytochrome bd from Mycobacterium tuberculosis (Mtbd) is a menaquinol oxidase that has gained interest as an antibiotic target because of its importance in survival under infectious conditions. Mtbd contains a characteristic disulfide bond that has been hypothesized to allow for Mtbd activity regulation at the enzymatic level, possibly helping M. tuberculosis to rapidly adapt to the hostile environment of the phagosome. Here, the role of the disulfide bond and quinone specificity have been determined by reconstitution of a minimal respiratory chain and the single-particle cryo-EM structure in the disulfide-reduced form. Mtbd was shown to be specific for menaquinone, while regulation by reduction of the Q-loop disulfide bond decreased oxidase activity up to 90%. Structural analysis shows that a salt bridge unique to Mtbd keeps the Q-loop partially structured in its disulfide-reduced form, which could facilitate the rapid activation of Mtbd upon exposure to reactive oxygen species. We signify Mtbd as the first redox sensory terminal oxidase and propose that this helps M. tuberculosis in the defense against reactive oxygen species encountered during infection.

01 Jan 2025·Infection, Genetics and Evolution

Europe-wide distribution and bat-host specific lineages in the malarial parasite Polychromophilus murinus revealed through genetic screening of bat flies

Article

Author: Timm, Luisa ; van Schaik, Jaap ; Rosskopf, Sascha P ; Schaer, Juliane ; Werb, Oskar

Malaria parasites of the genus Polychromophilus commonly infect vespertilionid and miniopterid bats, and are transmitted by bat flies (Nycteribiidae). While Polychromophilus murinus has been recorded sporadically in Europe, its host range, distribution and phylogeographic structure have not been explored. Here we investigate the prevalence and genetic diversity of P. murinus infections in 1131 bat flies collected from seven European bat species, focusing on Basilia nana, collected from its primary host, the Bechstein's bat throughout its distribution. Additionally, we explore the temporal dynamics of P. murinus in two regions in Germany where bat flies were repeatedly collected over at least five years. Bat flies were screened for Polychromophilus infection via PCR of a fragment of cytochrome b, and fragments of three additional genes were sequenced for positive samples. Overall, P. murinus infections were detected in 287 of 1131 screened bat flies of four different species, collected from seven bat species, across 13 countries. The 269 recovered cytb sequences represented 21 distinct haplotypes, clustered based on the bat species from which the infected flies were collected. Repeated sampling over multiple years revealed a consistent presence of P. murinus in both investigated populations, without substantial variation in prevalence between years. The results suggest an endemic long-term presence of Polychromophilus within European bat populations, and the presence of host-specific associations between P. murinus lineages and its various bat hosts. We posit that exposure to P. murinus appears to be a near certainty in several European bat species, and its potential costs should be further investigated.

01 Jan 2025·Biochimica et Biophysica Acta (BBA) - Bioenergetics

Requirement of Bacillus subtilis succinate:menaquinone oxidoreductase activity for membrane energization depends on the direction of catalysis

Article

Author: Azarkina, Natalia V ; Azarkina, Natalia V.

Succinate:quinone oxidoreductases (SQR) from Bacilli catalyze reduction of menaquinone by succinate, as well as the reverse reaction. The direct activity is energetically unfavorable and lost upon ΔμН⁺ dissipation, thus suggesting ΔμН⁺ to be consumed during catalysis. Paradoxically, the generation of ΔμН⁺ upon fumarate reduction was never confirmed. Thus, the exact role of ΔμН⁺ in the operation of bacillary-type SQRs remained questionable. The purpose of this work was to clarify this issue. We have described the different operating modes of the membrane-bound SQR from Bacillus subtilis. Tightly coupled membrane vesicles from both wild-type cells and the mutant containing cytochrome bd as the only terminal oxidase were studied. This made it possible to compare the respiratory chains with 2 versus 1H⁺/e^- stoichiometry of ΔμН⁺ generation. Direct and reverse activities of SQR were determined under either energized or deenergized conditions. The wild-type membranes demonstrated high succinate oxidase activity very sensitive to uncoupling. On the contrary, the mutant showed extremely low succinate oxidase activity resistant to uncoupling. ΔμН⁺ generation at the cost of ATP hydrolysis restored the uncoupling sensitive succinate respiration in the mutant. Membranes of the both types effectively reduced fumarate by menaquinol. This activity was not affected by energization or uncoupling, neither it was followed by ΔμН⁺ generation. Thus, B. subtilis SQR demonstrates two regimes: ΔμН⁺-coupled and not coupled. This behavior can be explained by assuming the presence of two menaquinone binding sites which drastically differ in affinity for the oxidized and reduced substrate.

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Cytochrome b

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