scholarly journals Assembly pathway of a bacterial complex iron sulfur molybdoenzyme

2017 ◽  
Vol 8 (3-4) ◽  
pp. 155-167 ◽  
Author(s):  
Stephana J. Cherak ◽  
Raymond J. Turner
Keyword(s):  
Anaerobic Respiration ◽  
Dmso Reductase ◽  
Complex Processes ◽  
Final Assembly ◽  
Iron Sulfur ◽  
Maturation Protein ◽  
Final Electron ◽  
Protein Folding And Assembly ◽  
Bacterial Complex ◽  
Final Electron Acceptor

AbstractProtein folding and assembly into macromolecule complexes within the living cell are complex processes requiring intimate coordination. The biogenesis of complex iron sulfur molybdoenzymes (CISM) requires use of a system specific chaperone – a redox enzyme maturation protein (REMP) – to help mediate final folding and assembly. The CISM dimethyl sulfoxide (DMSO) reductase is a bacterial oxidoreductase that utilizes DMSO as a final electron acceptor for anaerobic respiration. The REMP DmsD strongly interacts with DMSO reductase to facilitate folding, cofactor-insertion, subunit assembly and targeting of the multi-subunit enzyme prior to membrane translocation and final assembly and maturation into a bioenergetic catalytic unit. In this article, we discuss the biogenesis of DMSO reductase as an example of the participant network for bacterial CISM maturation pathways.

Anaerobic Growth of Acidithiobacillus ferrooxidans on Pyrite

2013 ◽  
Vol 825 ◽  
pp. 96-99
Author(s):  
Blanca Escobar ◽  
Tomas Vargas
Keyword(s):  
Electron Acceptor ◽  
Bacterial Growth ◽  
Ferrous Iron ◽  
Elemental Sulfur ◽  
Ferric Iron ◽  
Anaerobic Respiration ◽  
Anaerobic Growth ◽  
Final Electron ◽  
Anaerobic Reduction ◽  
Final Electron Acceptor

In the bioleaching of mineral sulphides under the catalytic action ofAt. ferrooxidans,ferrous ion oxidation and sulfides/sulfur solubilization uses oxygen as the final electron acceptor. Also, under anaerobic conditions,At. ferrooxidanscan alternatively catalize the oxidation of sulfur or reduced inorganic sulfur compounds (RISC) using ferric iron as electron acceptor [1]. The formation of Fe (II) from pyrite and covellite in the ferric anaerobic bioleaching withA. ferrooxidans,has been studied and well documented [2,3]. The requirements of ferric iron as electron acceptor for the anaerobic growth ofAt. ferrooxidanson elemental sulfur has been demonstrated and a linear relationship was obtained between the concentration of ferrous iron accumulated in the cultures and the increase in cell density [4]. It has been suggested a possible role in the solubilization of metals from sulfide ores involving the participation of the enzyme sulfur (sulfide): Fe (III) oxidoreductase [5]. Bacterial growth ofAt. ferrooxidanshas also been reported in the oxidative anaerobic respiration using hydrogen as electron donor and ferric iron as electron acceptor [6]. Anaerobic reduction of ferric iron and ferrous iron production from pyrite byAt. ferrooxidanshas been demonstrated [2], however there are no reports about bacterial growth using this mineral. In this work, we studied the anaerobic bioleaching of pyrite with the aim to determine ifAt. ferrooxidansis capable to anaerobic growth on pyrite using ferric iron as electron acceptor.

Reduction of selenate and selenite to elemental selenium by Wolinella succinogenes

1992 ◽  
Vol 38 (12) ◽  
pp. 1328-1333 ◽  
Author(s):  
Francisco A. Tomei ◽  
Larry L. Barton ◽  
Cheryl L. Lemanski ◽  
Thomas G. Zocco
Keyword(s):  
Stationary Growth Phase ◽  
Elemental Selenium ◽  
Bacterial Cells ◽  
Wolinella Succinogenes ◽  
Stationary Growth ◽  
X Ray ◽  
Dense Granules ◽  
Transmission Electron ◽  
Final Electron ◽  
Final Electron Acceptor

Cultures of Wolinella succinogenes were adapted to grow in the presence of 1 mM [Formula: see text] or 10 mM [Formula: see text]. Both selenium salts were reduced to red, amorphous, elemental selenium but only after the culture reached the stationary growth phase. Bacterial cells taken from a culture actively reducing selenium were examined by transmission electron microscopy and were found to have large, electron-dense granules in the cytoplasm. These granules were verified by energy-dispersive X-ray spectroscopy to consist of selenium. Wolinella succinogenes was unable to grow with [Formula: see text] or [Formula: see text] as the final electron acceptor. Key words: Wolinella, selenium, cytology, selenate.

scholarly journals HISTOCHEMICAL DEMONSTRATION OF 3α-HYDROXYSTEROID DEHYDROGENASE ACTIVITY

1966 ◽  
Vol 14 (1) ◽  
pp. 77-83 ◽  
Author(s):  
KÁROLY BALOGH
Keyword(s):  
Leydig Cells ◽  
Hydroxysteroid Dehydrogenase ◽  
Histochemical Demonstration ◽  
Female Rats ◽  
Ventral Prostate ◽  
Tetrazolium Salt ◽  
Rat Tissues ◽  
Final Electron ◽  
Nucleotide Specificity ◽  
Final Electron Acceptor

The reversible oxidation of 3α-hydroxysteroids to their corresponding 3-keto forms comprises an important step in the metabolism of C19-steroids. The described techniquue demonstrates the activity of the enzyme catalyzing this reaction, with the use of androsterone as a substrate and a tetrazolium salt as the final electron acceptor. The enzyme is specific for 3α-hydroxysteroids; there was no histochemical reaction with epiandrosterone, the β isomer of androsterone. Since 3α-hydroxysteroid dehydrogenase is soluble in aqueous solutions, it was necessary to increase the osmolarity of the incubation medium by adding polyvinylpyrrolidone in a final concentration of 20%. Although the enzyme has a dual nucleotide specificity, no appreciable differences were seen in its distribution pattern in rat tissues with either NAD or NADP as a coenzyme. In adult female rats, enzyme activity was present in the liver, kidneys and clitoral glands. In mature males, diformazan deposits were observed in the liver, kidneys, preputiai glands, epididymis, ventral prostate and Leydig cells.

Biochemical and regulatory properties of a respiratory island encoded by a conjugative plasmid in the extreme thermophile Thermus thermophilus

2006 ◽  
Vol 34 (1) ◽  
pp. 97-100 ◽  
Author(s):  
F. Cava ◽  
J. Berenguer
Keyword(s):  
Nadh Dehydrogenase ◽  
Current Knowledge ◽  
Thermus Thermophilus ◽  
Thermophilic Bacterium ◽  
Conjugative Plasmid ◽  
Nitrate Respiration ◽  
Final Electron ◽  
New Type ◽  
Regulatory Properties ◽  
Final Electron Acceptor

In the present paper, we summarize the current knowledge on the first step of the denitrification pathway in the ancestral extreme thermophilic bacterium Thermus thermophilus. In this organism, nitrate respiration is performed by a mobilizable respiratory island that encodes a new type of respiratory NADH dehydrogenase as electron donor, a tetrameric membrane nitrate reductase as final electron acceptor, two nitrate/nitrite transporters and the transcription factors required for their expression in response to nitrate and anoxia.

Metabolism

2017 ◽  
Author(s):  
Andrew Clarke
Keyword(s):  
Resting Metabolic Rate ◽  
Intermediary Metabolism ◽  
Donor And Acceptor ◽  
Daily Energy ◽  
Resting Metabolism ◽  
Final Electron ◽  
The Difference ◽  
Electron Donor And Acceptor ◽  
Final Electron Acceptor ◽  
Atp Regeneration

Metabolism is driven by redox reactions, in which part of the difference in potential energy between the electron donor and acceptor is used by the organism for its life processes (with the remainder being dissipated as heat). The key process is intermediary metabolism, by which the energy stored in reserves (glycogen, starch, lipid, protein) is transferred to ATP. In aerobic respiration the electrons released from reserves are passed to oxygen, which is thereby reduced to water. Not all ATP regeneration involves oxygen as the final electron acceptor, and not all oxygen is used for ATP regeneration, but oxygen consumption is often the simplest and most practical way to measure the rate of intermediary metabolism and the errors in doing so are believed to be small. The costs of existence, as estimated by resting metabolism, represent only a part (~ 25%) of the daily energy expenditure of organisms. The costs of the organism’s ecology (growth, reproduction, movement and so on) are additional to existence costs. Resting metabolic rate increases with cell temperature, indicating that it costs more energy to maintain a warm cell than it does a cool or cold cell. The temperature sensitivity of resting metabolism is highly conserved across organisms.

scholarly journals Molecular Dissection of Bacterial Nanowires

mBio ◽  
2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Thomas Boesen ◽  
Lars Peter Nielsen
Keyword(s):  
Conclusive Evidence ◽  
Geobacter Sulfurreducens ◽  
Electron Conduction ◽  
Content Type ◽  
Type Iv ◽  
Pilin Subunit ◽  
Type Iv Pilin ◽  
Final Electron ◽  
Conductive Properties ◽  
Final Electron Acceptor

ABSTRACTThe discovery of bacterial conductive structures, termed nanowires, has intrigued scientists for almost a decade. Nanowires enable bacteria to transfer electrons over micrometer distances to extracellular electron acceptors such as insoluble metal oxides or electrodes. Nanowires are pilus based and inGeobacter sulfurreducensare composed of the type IV pilin subunit PilA. Multihemec-type cytochromes have been shown to attach to nanowire pili. Two hypotheses have been proposed for electron conduction in nanowires. The first (termed the metal-like conductivity or MLC hypothesis) claims that the pilus itself has the electron-conductive properties and the attached cytochromes mediate transfer to the final electron acceptor, whereas the second hypothesis (termed the superexchange conductivity or SEC hypothesis) suggests that electrons are “hopping” between heme groups in cytochromes closely aligned with the pilus as a scaffold. In their recent article inmBio, Vargas et al. [M. Vargas, N. S. Malvankar, P.-L. Tremblay, C. Leang, J. A. Smith, P. Patel, O. Snoeyenbos-West, K. P. Nevin, and D. R. Lovley, mBio 4(2):e00210-13, 2013] address this ambiguity through an analysis of strain Aro-5, aG. sulfurreducensPilA mutant lacking aromatic residues in the nonconserved portion of PilA. These residues were suspected of involvement in electron transport according to the MLC hypothesis. TheG. sulfurreducensmutant had reduced conductive properties, lending important support to the MLC hypothesis. The data also highlight the need for further and more conclusive evidence for one or the other hypothesis.

Anaerobic biodegradation of BTEX using Mn(IV) and Fe(III) as alternative electron acceptors

2003 ◽  
Vol 48 (6) ◽  
pp. 125-131 ◽  
Author(s):  
W.R. Villatoro-Monzón ◽  
A.M. Mesta-Howard ◽  
E. Razo-Flores
Keyword(s):  
Manganese Oxide ◽  
Electron Acceptor ◽  
Anaerobic Biodegradation ◽  
Electron Acceptors ◽  
Batch Experiments ◽  
First Report ◽  
Reducing Conditions ◽  
Final Electron ◽  
Amorphous Manganese Oxide ◽  
Final Electron Acceptor

Anaerobic BTEX biodegradation was tested in batch experiments using an anaerobic sediment as inoculum under Fe(III) and Mn(IV) reducing conditions. All BTEX were degraded under the conditions tested, specially under Mn(IV) reducing conditions, where benzene was degraded at a rate of 0.8 μmol l-1d-1, significantly much faster than Fe(III) reducing conditions. Under Fe(III) reducing conditions, ethylbenzene was the compound that degraded at the faster rate of 0.19 μmol l-1d-1. Mn(IV) reducing conditions are energetically more favourable than Fe(III), therefore, BTEX were more rapidly degraded under Mn(IV) reducing conditions. These results represent the first report of the degradation of benzene with Mn(IV) as the final electron acceptor. Amorphous manganese oxide is a natural widely distributed metal in groundwater, where it can be microbiologically reduced, leading to the degradation of monoaromatic compounds.

scholarly journals Anaerobic α-Amylase Production and Secretion with Fumarate as the Final Electron Acceptor in Saccharomyces cerevisiae

2013 ◽  
Vol 79 (9) ◽  
pp. 2962-2967 ◽  
Author(s):  
Zihe Liu ◽  
Tobias Österlund ◽  
Jin Hou ◽  
Dina Petranovic ◽  
Jens Nielsen
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Folding ◽  
Protein Secretion ◽  
Electron Acceptor ◽  
Anaerobic Growth ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Content Type ◽  
Final Electron ◽  
Final Electron Acceptor

ABSTRACTIn this study, we focus on production of heterologous α-amylase in the yeastSaccharomyces cerevisiaeunder anaerobic conditions. We compare the metabolic fluxes and transcriptional regulation under aerobic and anaerobic conditions, with the objective of identifying the final electron acceptor for protein folding under anaerobic conditions. We find that yeast produces more amylase under anaerobic conditions than under aerobic conditions, and we propose a model for electron transfer under anaerobic conditions. According to our model, during protein folding the electrons from the endoplasmic reticulum are transferred to fumarate as the final electron acceptor. This model is supported by findings that the addition of fumarate under anaerobic (but not aerobic) conditions improves cell growth, specifically in the α-amylase-producing strain, in which it is not used as a carbon source. Our results provide a model for the molecular mechanism of anaerobic protein secretion using fumarate as the final electron acceptor, which may allow for further engineering of yeast for improved protein secretion under anaerobic growth conditions.

scholarly journals Biology of Ageing and Role of Dietary Antioxidants

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Cheng Peng ◽  
Xiaobo Wang ◽  
Jingnan Chen ◽  
Rui Jiao ◽  
Lijun Wang ◽  
...  
Keyword(s):  
Antioxidant Defense ◽  
Antioxidant Defense System ◽  
Fruit Flies ◽  
Dietary Antioxidants ◽  
Final Electron ◽  
Underlying Mechanisms ◽  
The One ◽  
Final Electron Acceptor ◽  
In Cells

Interest in relationship between diet and ageing is growing. Research has shown that dietary calorie restriction and some antioxidants extend lifespan in various ageing models. On the one hand, oxygen is essential to aerobic organisms because it is a final electron acceptor in mitochondria. On the other hand, oxygen is harmful because it can continuously generate reactive oxygen species (ROS), which are believed to be the factors causing ageing of an organism. To remove these ROS in cells, aerobic organisms possess an antioxidant defense system which consists of a series of enzymes, namely, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR). In addition, dietary antioxidants including ascorbic acid, vitamin A, vitamin C,α-tocopherol, and plant flavonoids are also able to scavenge ROS in cells and therefore theoretically can extend the lifespan of organisms. In this connection, various antioxidants including tea catechins, theaflavins, apple polyphenols, black rice anthocyanins, and blueberry polyphenols have been shown to be capable of extending the lifespan of fruit flies. The purpose of this review is to brief the literature on modern biological theories of ageing and role of dietary antioxidants in ageing as well as underlying mechanisms by which antioxidants can prolong the lifespan with focus on fruit flies as an model.

Sign in / Sign up

Export Citation Format

Share Document