scholarly journals Impact of Molecular Hydrogen on Chalcopyrite Bioleaching by the Extremely Thermoacidophilic Archaeon Metallosphaera sedula

2010 ◽  
Vol 76 (8) ◽  
pp. 2668-2672 ◽  
Author(s):  
Kathryne S. Auernik ◽  
Robert M. Kelly
Keyword(s):  
Energy Source ◽  
Electron Transport ◽  
Molecular Hydrogen ◽  
Electron Transport Chain ◽  
Open Reading Frames ◽  
Terminal Oxidase ◽  
Metallosphaera Sedula ◽  
Transport Chain ◽  
Heterotrophic Metabolism ◽  
Reading Frames

ABSTRACT Hydrogen served as a competitive inorganic energy source, impacting the CuFeS 2 bioleaching efficiency of the extremely thermoacidophilic archaeon Metallosphaera sedula. Open reading frames encoding key terminal oxidase and electron transport chain components were triggered by CuFeS2. Evidence of heterotrophic metabolism was noted after extended periods of bioleaching, presumably related to cell lysis.

scholarly journals The oxidation of nicotinic acid by Pseudomonas ovalis Chester. The terminal oxidase

1972 ◽  
Vol 129 (3) ◽  
pp. 755-761 ◽  
Author(s):  
M. V. Jones ◽  
D. E. Hughes
Keyword(s):  
Electron Transport ◽  
Nicotinic Acid ◽  
Electron Transport Chain ◽  
Acid Oxidase ◽  
Terminal Oxidase ◽  
Difference Spectra ◽  
Terminal Oxidases ◽  
Cytochrome O ◽  
Transport Chain ◽  
Terminal Oxidation

In cell-free extracts of Pseudomonas ovalis nicotinic acid oxidase is confined to the wallmembrane fraction. It is associated with an electron-transport chain comprising b- and c-type cytochromes only, differing proportions of which are reduced by nicotinate and NADH. CO difference-spectra show two CO-binding pigments, cytochrome o (absorption maximum at 417nm) and another component absorbing maximally at 425nm. Cytochrome o is not reduced by NADH or by succinate but is by nicotinate, which can also reduce the ‘425’ CO-binding pigment. The effects of inhibitors of terminal oxidation support the idea of two terminal oxidases and a scheme involving the ‘425’ CO-binding pigment and the other components of the electron-transport chain is proposed.

scholarly journals The energy-linked transhydrogenase reaction in respiratory mutants of Escherichia coli K 12

1971 ◽  
Vol 125 (2) ◽  
pp. 489-493 ◽  
Author(s):  
G. B. Cox ◽  
N. A. Newton ◽  
J. D. Butlin ◽  
F. Gibson
Keyword(s):  
Escherichia Coli ◽  
Energy Source ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Adenosine Triphosphatase ◽  
E Coli ◽  
Transport Chain ◽  
Mutant Strains ◽  
K 12 ◽  
A Site

1. Energy-linked and non-energy-linked transhydrogenase activities were assayed in membrane preparations from normal Escherichia coli K 12 and from various mutant strains. 2. The energy-linked transhydrogenase, which uses ATP as energy source, was dependent for activity on the presence of a functional Mg2++Ca2+-stimulated adenosine triphosphatase. 3. Neither of the quinones formed by E. coli, namely ubiquinone-8 and menaquinone-8, was required for normal ATP-dependent energy-linked transhydrogenase activity. 4. The energy-linked transhydrogenase was inhibited by piericidin A at a site unrelated to the sites of inhibition of the electron-transport chain by piericidin A.

scholarly journals Terminal Respiratory Oxidases: A Targetables Vulnerability of Mycobacterial Bioenergetics?

2020 ◽  
Vol 10 ◽  
Author(s):  
Sapna Bajeli ◽  
Navin Baid ◽  
Manjot Kaur ◽  
Ganesh P. Pawar ◽  
Vinod D. Chaudhari ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Transport ◽  
Molecular Oxygen ◽  
Electron Transport Chain ◽  
Drug Targets ◽  
Atp Synthesis ◽  
Terminal Oxidase ◽  
Terminal Oxidases ◽  
Transport Chain ◽  
Synthase Inhibitor

Recently, ATP synthase inhibitor Bedaquiline was approved for the treatment of multi-drug resistant tuberculosis emphasizing the importance of oxidative phosphorylation for the survival of mycobacteria. ATP synthesis is primarily dependent on the generation of proton motive force through the electron transport chain in mycobacteria. The mycobacterial electron transport chain utilizes two terminal oxidases for the reduction of oxygen, namely the bc1-aa3 supercomplex and the cytochrome bd oxidase. The bc1-aa3 supercomplex is an energy-efficient terminal oxidase that pumps out four vectoral protons, besides consuming four scalar protons during the transfer of electrons from menaquinone to molecular oxygen. In the past few years, several inhibitors of bc1-aa3 supercomplex have been developed, out of which, Q203 belonging to the class of imidazopyridine, has moved to clinical trials. Recently, the crystal structure of the mycobacterial cytochrome bc1-aa3 supercomplex was solved, providing details of the route of transfer of electrons from menaquinone to molecular oxygen. Besides providing insights into the molecular functioning, crystal structure is aiding in the targeted drug development. On the other hand, the second respiratory terminal oxidase of the mycobacterial respiratory chain, cytochrome bd oxidase, does not pump out the vectoral protons and is energetically less efficient. However, it can detoxify the reactive oxygen species and facilitate mycobacterial survival during a multitude of stresses. Quinolone derivatives (CK-2-63) and quinone derivative (Aurachin D) inhibit cytochrome bd oxidase. Notably, ablation of both the two terminal oxidases simultaneously through genetic methods or pharmacological inhibition leads to the rapid death of the mycobacterial cells. Thus, terminal oxidases have emerged as important drug targets. In this review, we have described the current understanding of the functioning of these two oxidases, their physiological relevance to mycobacteria, and their inhibitors. Besides these, we also describe the alternative terminal complexes that are used by mycobacteria to maintain energized membrane during hypoxia and anaerobic conditions.

scholarly journals Identification of Components of Electron Transport Chains in the Extremely Thermoacidophilic Crenarchaeon Metallosphaera sedula through Iron and Sulfur Compound Oxidation Transcriptomes

2008 ◽  
Vol 74 (24) ◽  
pp. 7723-7732 ◽  
Author(s):  
Kathryne S. Auernik ◽  
Robert M. Kelly
Keyword(s):  
Electron Transport ◽  
Ferrous Iron ◽  
Sulfur Oxidation ◽  
Open Reading Frames ◽  
Transcriptional Analysis ◽  
Sequence Information ◽  
Proton Pumps ◽  
Terminal Oxidase ◽  
Heterodisulfide Reductase ◽  
Metallosphaera Sedula

ABSTRACT The crenarchaeal order Sulfolobales collectively contain at least five major terminal oxidase complexes. Based on genome sequence information, all five complexes are found only in Metallosphaera sedula and Sulfolobus tokodaii, the two sequenced Sulfolobales capable of iron oxidization. While specific respiratory complexes in certain Sulfolobales have been characterized previously as proton pumps for maintaining intracellular pH and generating proton motive force, their contribution to sulfur and iron biooxidation has not been considered. For M. sedula growing in the presence of ferrous iron and reduced inorganic sulfur compounds (RISCs), global transcriptional analysis was used to track the response of specific genes associated with these complexes, as well as other known and putative respiratory electron transport chain elements. Open reading frames from all five terminal oxidase or bc 1-like complexes were stimulated on one or more conditions tested. Components of the fox (Msed0467 to Msed0489) and soxNL-cbsABA (Msed0500 to Msed0505) terminal/quinol oxidase clusters were triggered by ferrous iron, while the soxABCDD′ terminal oxidase cluster (Msed0285 to Msed0291) were induced by tetrathionate and S0. Chemolithotrophic electron transport elements, including a putative tetrathionate hydrolase (Msed0804), a novel polysulfide/sulfur/dimethyl sulfoxide reductase-like complex (Msed0812 to Msed0818), and a novel heterodisulfide reductase-like complex (Msed1542 to Msed1550), were also stimulated by RISCs. Furthermore, several hypothetical proteins were found to have strong responses to ferrous iron or RISCs, suggesting additional candidates in iron or sulfur oxidation-related pathways. From this analysis, a comprehensive model for electron transport in M. sedula could be proposed as the basis for examining specific details of iron and sulfur oxidation in this bioleaching archaeon.

scholarly journals AB0031 T HELPER 17 CELLS WERE SIGNIFICANTLY DECREASED BY MITOCHONDRIAL ELECTRON TRANSPORT CHAIN COMPLEX INHIBITOR IN PATIENTS WITH RHEUMATOID ARTHRITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1318.2-1318
Author(s):  
H. R. Lee ◽  
S. J. Yoo ◽  
J. Kim ◽  
I. S. Yoo ◽  
C. K. Park ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Electron Transport ◽  
Disease Activity ◽  
Th17 Cells ◽  
Electron Transport Chain ◽  
Chain Complex ◽  
Complex Iii ◽  
Mitochondrial Electron Transport Chain ◽  
Transport Chain ◽  
Healthy Control

Background:Reactive oxygen species (ROS) and T helper 17 (TH17) cells have been known to play an important role in the pathogenesis of rheumatoid arthritis (RA). However, the interrelationship between ROS and TH17 remains unclear in RAObjectives:To explore whether ROS affect TH17 cells in peripheral blood mononuclear cells (PBMC) of RA patients, we analyzed ROS expressions among T cell subsets following treatment with mitochondrial electron transport chain complex inhibitors.Methods:Blood samples were collected from 40 RA patients and 10 healthy adult volunteers. RA activity was divided according to clinical parameter DAS28. PBMC cells were obtained from the whole blood using lymphocyte separation medium density gradient centrifugation. Following PBMC was stained with Live/Dead stain dye, cells were incubated with antibodies for CD3, CD4, CD8, and CD25. After fixation and permeabilization, samples were stained with antibodies for FoxP3 and IL-17A. MitoSox were used for mitochondrial specific staining.Results:The frequency of TH17 cells was increased by 4.83 folds in moderate disease activity group (5.1>DAS28≥3.2) of RA patients compared to healthy control. Moderate RA activity patients also showed higher ratio of TH17/Treg than healthy control (3.57 folds). All RA patients had elevated expression of mitochondrial specific ROS than healthy control. When PBMC cells were treated with 2.5uM of antimycin A (mitochondrial electron transport chain complex III inhibitor) for 16 h, the frequency of TH17 cells was significantly decreased.Conclusion:The mitochondrial electron transport chain complex III inhibitor markedly downregulated the frequency of TH17 cells in moderate disease activity patients with RA. These findings provide a novel approach to regulate TH17 function in RA through mitochondrial metabolism related ROS production.References:[1]Szekanecz, Z., et al., New insights in synovial angiogenesis. Joint Bone Spine, 2010. 77(1): p. 13-9.[2]Prevoo, M.L., et al., Modified disease activity scores that include twenty-eight-joint counts. Development and validation in a prospective longitudinal study of patients with rheumatoid arthritis. Arthritis Rheum, 1995. 38(1): p. 44-8.Disclosure of Interests:None declared

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