Related Research Articles
Cytochromes are redox-active proteins containing a heme, with a central Fe atom at its core, as a cofactor. They are involved in electron transport chain and redox catalysis. They are classified according to the type of heme and its mode of binding. Four varieties are recognized by the International Union of Biochemistry and Molecular Biology (IUBMB), cytochromes a, cytochromes b, cytochromes c and cytochrome d.
An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples this electron transfer with the transfer of protons (H+ ions) across a membrane. The electrons that transferred from NADH and FADH2 to the ETC involves 4 multi-subunit large enzymes complexes and 2 mobile electron carriers. Many of the enzymes in the electron transport chain are membrane-bound.
The enzyme cytochrome c oxidase or Complex IV, is a large transmembrane protein complex found in bacteria, archaea, and mitochondria of eukaryotes.
The coenzyme Q : cytochrome c – oxidoreductase, sometimes called the cytochrome bc1 complex, and at other times complex III, is the third complex in the electron transport chain, playing a critical role in biochemical generation of ATP. Complex III is a multisubunit transmembrane protein encoded by both the mitochondrial and the nuclear genomes. Complex III is present in the mitochondria of all animals and all aerobic eukaryotes and the inner membranes of most eubacteria. Mutations in Complex III cause exercise intolerance as well as multisystem disorders. The bc1 complex contains 11 subunits, 3 respiratory subunits, 2 core proteins and 6 low-molecular weight proteins.
Succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR) or respiratory complex II is an enzyme complex, found in many bacterial cells and in the inner mitochondrial membrane of eukaryotes. It is the only enzyme that participates in both the citric acid cycle and the electron transport chain. Histochemical analysis showing high succinate dehydrogenase in muscle demonstrates high mitochondrial content and high oxidative potential.
Geobacter is a genus of bacteria. Geobacter species are anaerobic respiration bacterial species which have capabilities that make them useful in bioremediation. Geobacter was found to be the first organism with the ability to oxidize organic compounds and metals, including iron, radioactive metals, and petroleum compounds into environmentally benign carbon dioxide while using iron oxide or other available metals as electron acceptors. Geobacter species are also found to be able to respire upon a graphite electrode. They have been found in anaerobic conditions in soils and aquatic sediment.
The cytochrome b6f complex is an enzyme found in the thylakoid membrane in chloroplasts of plants, cyanobacteria, and green algae, that catalyzes the transfer of electrons from plastoquinol to plastocyanin. The reaction is analogous to the reaction catalyzed by cytochrome bc1 of the mitochondrial electron transport chain. During photosynthesis, the cytochrome b6f complex is one step along the chain that transfers electrons from Photosystem II to Photosystem I, and at the same time pumps protons into the thylakoid space, contributing to the generation of an electrochemical (energy) gradient that is later used to synthesize ATP from ADP.
Iron-binding proteins are carrier proteins and metalloproteins that are important in iron metabolism and the immune response. Iron is required for life.
Formate dehydrogenases are a set of enzymes that catalyse the oxidation of formate to carbon dioxide, donating the electrons to a second substrate, such as NAD+ in formate:NAD+ oxidoreductase (EC 1.17.1.9) or to a cytochrome in formate:ferricytochrome-b1 oxidoreductase (EC 1.2.2.1).
Shewanella oneidensis is a bacterium notable for its ability to reduce metal ions and live in environments with or without oxygen. This proteobacterium was first isolated from Lake Oneida, NY in 1988, hence its name.
Bacterial nanowires are electrically conductive appendages produced by a number of bacteria most notably from the Geobacter and Shewanella genera. Conductive nanowires have also been confirmed in the oxygenic cyanobacterium Synechocystis PCC6803 and a thermophilic, methanogenic coculture consisting of Pelotomaculum thermopropionicum and Methanothermobacter thermoautotrophicus. From physiological and functional perspectives, bacterial nanowires are diverse. The precise role microbial nanowires play in their biological systems has not been fully realized, but several proposed functions exist. Outside of a naturally occurring environment, bacterial nanowires have shown potential to be useful in several fields, notably the bioenergy and bioremediation industries.
An exoelectrogen normally refers to a microorganism that has the ability to transfer electrons extracellularly. While exoelectrogen is the predominant name, other terms have been used: electrochemically active bacteria, anode respiring bacteria, and electricigens. Electrons exocytosed in this fashion are produced following ATP production using an electron transport chain (ETC) during oxidative phosphorylation. Conventional cellular respiration requires a final electron acceptor to receive these electrons. Cells that use molecular oxygen (O2) as their final electron acceptor are described as using aerobic respiration, while cells that use other soluble compounds as their final electron acceptor are described as using anaerobic respiration. However, the final electron acceptor of an exoelectrogen is found extracellularly and can be a strong oxidizing agent in aqueous solution or a solid conductor/electron acceptor. Two commonly observed acceptors are iron compounds (specifically Fe(III) oxides) and manganese compounds (specifically Mn(III/IV) oxides). As oxygen is a strong oxidizer, cells are able to do this strictly in the absence of oxygen.
Geothrix fermentans is a rod-shaped, anaerobic bacterium. It is about 0.1 µm in diameter and ranges from 2-3 µm in length. Cell arrangement occurs singly and in chains. Geothrix fermentans can normally be found in aquatic sediments such as in aquifers. As an anaerobic chemoorganotroph, this organism is best known for its ability to use electron acceptors Fe(III), as well as other high potential metals. It also uses a wide range of substrates as electron donors. Research on metal reduction by G. fermentans has contributed to understanding more about the geochemical cycling of metals in the environment.
Geobacter sulfurreducens is a gram-negative metal and sulphur-reducing proteobacterium. It is rod-shaped, obligately anaerobic, non-fermentative, has flagellum and type four pili, and is closely related to Geobacter metallireducens. Geobacter sulfurreducens is an anaerobic species of bacteria that comes from the family of bacteria called Geobacteraceae. Under the genus of Geobacter, G. sulfurreducens is one out of twenty different species. The Geobacter genus was discovered by Derek R. Lovley in 1987. G. sulfurreducens was first isolated in Norman, Oklahoma, USA from materials found around the surface of a contaminated ditch.
Cytochrome d, previously known as cytochrome a2, is a name for all cytochromes that contain heme D as a cofactor. Two unrelated classes of cytochrome d are known: Cytochrome bd, an enzyme that generates a charge across the membrane so that protons will move, and cytochrome cd1, a nitrite reductase.
Geobacter psychrophilus is a Fe(III)-reducing bacterium. It is Gram-negative, slightly curved, rod-shaped and motile via means of monotrichous flagella. Its type strain is P35T.
Dissimilatory metal-reducing microorganisms are a group of microorganisms (both bacteria and archaea) that can perform anaerobic respiration utilizing a metal as terminal electron acceptor rather than molecular oxygen (O2), which is the terminal electron acceptor reduced to water (H2O) in aerobic respiration. The most common metals used for this end are iron [Fe(III)] and manganese [Mn(IV)], which are reduced to Fe(II) and Mn(II) respectively, and most microorganisms that reduce Fe(III) can reduce Mn(IV) as well. But other metals and metalloids are also used as terminal electron acceptors, such as vanadium [V(V)], chromium [Cr(VI)], molybdenum [Mo(VI)], cobalt [Co(III)], palladium [Pd(II)], gold [Au(III)], and mercury [Hg(II)].
Geobacter daltonii is a Gram-negative, Fe(III)-reducing, Uranium(IV)-reducing and non-spore-forming bacterium from the genus of Geobacter which has been isolated from sediments from the Oak Ridge Field Research Center in Oak Ridge, Tennessee in the United States.
Geobacter uraniireducens is a gram-negative, rod-shaped, anaerobic, chemolithotrophic, mesophilic, and motile bacterium from the genus of Geobacter. G. uraniireducens has been found to reduce iron and uranium in sediment and soil. It is being studied for use in bioremediation projects due to its ability to reduce uranium and arsenic.
Gemma Reguera is a Spanish-American microbiologist and professor at Michigan State University. She is the editor-in-chief of the journal Applied and Environmental Microbiology and was elected fellow of the American Academy of Microbiology in 2019. She is the recipient of the 2022 Alice C. Evans Award for Advancement of Women from the American Society for Microbiology. Her lab's research is focused on electrical properties of metal-reducing microorganisms.
References
- ↑ Qian, X; Mester, T; Morgado, L; Arakawa, T; Sharma, ML; Inoue, K; Joseph, C; Salgueiro, CA; Maroney, MJ; Lovley, DR (2011). "Biochemical characterization of purified OmcS, a c-type cytochrome required for insoluble Fe(III) reduction in Geobacter sulfurreducens". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1807 (4): 404–412. doi: 10.1016/j.bbabio.2011.01.003 . PMID 21236241.
- ↑ Wang; et al. (2022). "Cryo-EM structure of an extracellular Geobacter OmcE cytochrome filament reveals tetrahaem packing". Nature Microbiology. doi:10.1038/s41564-022-01159-z. PMC 9357133 . PMID 35798889.
- ↑ Wang; et al. (2019). "Structure of Microbial Nanowires Reveals Stacked Hemes that Transport Electrons over Micrometers". Cell. doi:10.1016/j.cell.2019.03.029. PMC 6720112 . PMID 30951668.
- ↑ Butler; et al. (2012). "Comparative genomic analysis of Geobacter sulfurreducens KN400, a strain with enhanced capacity for extracellular electron transfer and electricity production". BMC Genomics. 13: 471. doi:10.1186/1471-2164-13-471. PMC 3495685 . PMID 22967216.
 | This enzyme-related article is a stub. You can help Wikipedia by expanding it. |