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Reverse Gyrase
Reverse gyrase is a type I topoisomerase that introduces positive supercoils into DNA, contrary to the typical negative supercoils introduced by the type II topoisomerase DNA gyrase. These positive supercoils can be introduced to DNA that is either negatively supercoiled or fully relaxed. Where DNA gyrase forms a tetramer and is capable of cleaving a double-stranded region of DNA, reverse gyrase can only cleave single stranded DNA. More specifically, reverse gyrase is a member of the type IA topoisomerase class; along with the ability to relax negatively or positively supercoiled DNA (which does not require ATP), type IA enzymes also tend to have RNA-topoisomerase activities. These RNA topoisomerases help keep longer RNA strands from becoming tangled in what are referred to as "pseudoknots." Due to their ability to interact with RNA, it is thought that this is one of the most ancient class of enzymes found to date. Reverse gyrase is an ATP-dependent topoisomerase in terms of its p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type I Topoisomerase
In molecular biology Type I topoisomerases are enzymes that cut one of the two strands of double-stranded DNA, relax the strand, and reanneal the strand. They are further subdivided into two structurally and mechanistically distinct topoisomerases: type IA and type IB. * Type IA topoisomerases change the linking number of a circular DNA strand by units of strictly 1. * Type IB topoisomerases change the linking number by multiples of 1 (n). Historically, type IA topoisomerases are referred to as prokaryotic topo I, while type IB topoisomerases are referred to as eukaryotic topoisomerase. This distinction, however, no longer applies as type IA and type IB topoisomerases exist in all domains of life. Functionally, these subclasses perform very specialized functions. Prokaryotic topoisomerase I (topo IA) can only relax negative supercoiled DNA, whereas eukaryotic topoisomerase I (topo IB) can introduce positive supercoils, separating the DNA of daughter chromosomes after DNA rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positive Supercoiling
DNA supercoiling refers to the amount of twist in a particular DNA strand, which determines the amount of strain on it. A given strand may be "positively supercoiled" or "negatively supercoiled" (more or less tightly wound). The amount of a strand’s supercoiling affects a number of biological processes, such as compacting DNA and regulating access to the genetic code (which strongly affects DNA metabolism and possibly gene expression). Certain enzymes, such as topoisomerases, change the amount of DNA supercoiling to facilitate functions such as DNA replication and transcription. The amount of supercoiling in a given strand is described by a mathematical formula that compares it to a reference state known as "relaxed B-form" DNA. Overview In a "relaxed" double-helical segment of B-DNA, the two strands twist around the helical axis once every 10.4–10.5 base pairs of sequence. Adding or subtracting twists, as some enzymes do, imposes strain. If a DNA segment under twist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type II Topoisomerase
Type II topoisomerases are topoisomerases that cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use the hydrolysis of ATP, unlike Type I topoisomerase. In this process, these enzymes change the linking number of circular DNA by ±2. Topoisomerases are ubiquitous enzymes, found in all living organisms. In animals, topoisomerase II is a chemotherapy target. In prokaryotes, gyrase is an antibacterial target. Indeed, these enzymes are of interest for a wide range of effects. Function Type II topoisomerases increase or decrease the linking number of a DNA loop by 2 units, and it promotes chromosome disentanglement. For example, DNA gyrase, a type II topoisomerase observed in '' E. coli'' and most other prokaryotes, introduces negative supercoils and decreases the linking number by 2. Gyrase is also able to remove knots from the bacterial chromosome. Along with gyrase, most prokaryotes also contain a second type IIA topoisomerase, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Gyrase
DNA gyrase, or simply gyrase, is an enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ... within the class of topoisomerase and is a subclass of Type II topoisomerases that reduces topological strain in an ATP dependent manner while double-stranded DNA is being unwound by elongating RNA polymerase, RNA-polymerase or by helicase in front of the progressing DNA replication#Replication fork, replication fork. The enzyme causes negative DNA supercoil, supercoiling of the DNA or relaxes positive supercoils. It does so by looping the template so as to form a crossing, then cutting one of the double helices and passing the other through it before releasing the break, changing the linking number by two in each enzymatic step. This process occurs in bacteria, whose single circular DNA is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicase
Helicases are a class of enzymes thought to be vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two hybridized nucleic acid strands (hence '' helic- + -ase''), using energy from ATP hydrolysis. There are many helicases, representing the great variety of processes in which strand separation must be catalyzed. Approximately 1% of eukaryotic genes code for helicases. The human genome codes for 95 non-redundant helicases: 64 RNA helicases and 31 DNA helicases. Many cellular processes, such as DNA replication, transcription, translation, recombination, DNA repair, and ribosome biogenesis involve the separation of nucleic acid strands that necessitates the use of helicases. Some specialized helicases are also involved in sensing of viral nucleic acids during infection and fulfill a immunological function. Function Helicases are o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topoisomerase
DNA topoisomerases (or topoisomerases) are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms, linked (catenated) and unlinked species, and knotted and unknotted DNA. Topological issues in DNA arise due to the intertwined nature of its double-helical structure, which, for example, can lead to overwinding of the DNA duplex during DNA replication and transcription. If left unchanged, this torsion would eventually stop the DNA or RNA polymerases involved in these processes from continuing along the DNA helix. A second topological challenge results from the linking or tangling of DNA during replication. Left unresolved, links between replicated DNA will impede cell division. The DNA topoisomerases prevent and correct these types of topological problems. They do this by binding to DNA and cutting the sugar-phosphate backbone of either one (type I topoisomerases) or both (type II topoisomerases) of the DNA strands. This transien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Gyrase Structure Figure
Reverse or reversing may refer to: Arts and media * ''Reverse'' (Eldritch album), 2001 * ''Reverse'' (2009 film), a Polish comedy-drama film * ''Reverse'' (2019 film), an Iranian crime-drama film * ''Reverse'' (Morandi album), 2005 * ''Reverse'' (TV series), a 2017–2018 South Korean television series *"Reverse", a 2014 song by SomeKindaWonderful * REVERSE art gallery, in Brooklyn, NY, US *Reverse tape effects including backmasking, the recording of sound in reverse * '' Reversing: Secrets of Reverse Engineering'', a book by Eldad Eilam *''Tegami Bachi: REVERSE'', the second season of the ''Tegami Bachi'' anime series, 2010 Driving * Reverse gear, in a motor or mechanical transmission * Reversing (vehicle maneuver), reversing the direction of a vehicle * Turning a vehicle through 180 degrees Sports and games *Reverse (American football), a trick play in American football *Reverse swing, a cricket delivery *Reverse (bridge), a type of bid in contract bridge Technology *Revers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesophile
A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, with an optimum growth range from . The optimum growth temperature for these organisms is 37°C. The term is mainly applied to microorganisms. Organisms that prefer extreme environments are known as extremophiles. Mesophiles have diverse classifications, belonging to two domains: Bacteria, Archaea, and to kingdom Fungi of domain Eucarya. Mesophiles belonging to the domain Bacteria can either be gram-positive or gram-negative. Oxygen requirements for mesophiles can be aerobic or anaerobic. There are three basic shapes of mesophiles: coccus, bacillus, and spiral. Habitat The habitats of mesophiles can include cheese and yogurt. They are often included during fermentation of beer and wine making. Since normal human body temperature is 37 °C, the majority of human pathogens are mesophiles, as are most of the organisms comprising the human microbiome. Mesophiles vs. extremophiles Meso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Supercoil
DNA supercoiling refers to the amount of twist in a particular DNA strand, which determines the amount of strain on it. A given strand may be "positively supercoiled" or "negatively supercoiled" (more or less tightly wound). The amount of a strand’s supercoiling affects a number of biological processes, such as compacting DNA and regulating access to the genetic code (which strongly affects DNA metabolism and possibly gene expression). Certain enzymes, such as topoisomerases, change the amount of DNA supercoiling to facilitate functions such as DNA replication and transcription. The amount of supercoiling in a given strand is described by a mathematical formula that compares it to a reference state known as "relaxed B-form" DNA. Overview In a "relaxed" double-helical segment of B-DNA, the two strands twist around the helical axis once every 10.4–10.5 base pairs of sequence. Adding or subtracting twists, as some enzymes do, imposes strain. If a DNA segment under twist s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermophile
A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earliest bacteria. Thermophiles are found in various geothermally heated regions of the Earth, such as hot springs like those in Yellowstone National Park (see image) and deep sea hydrothermal vents, as well as decaying plant matter, such as peat bogs and compost. Thermophiles can survive at high temperatures, whereas other bacteria or archaea would be damaged and sometimes killed if exposed to the same temperatures. The enzymes in thermophiles function at high temperatures. Some of these enzymes are used in molecular biology, for example the ''Taq'' polymerase used in PCR. "Thermophile" is derived from the el, θερμότητα (''thermotita''), meaning heat, and el, φίλια (''philia''), love. Classification Thermophiles can be c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Gyrase Mechanism
Reverse or reversing may refer to: Arts and media * ''Reverse'' (Eldritch album), 2001 * ''Reverse'' (2009 film), a Polish comedy-drama film * ''Reverse'' (2019 film), an Iranian crime-drama film * ''Reverse'' (Morandi album), 2005 * ''Reverse'' (TV series), a 2017–2018 South Korean television series *"Reverse", a 2014 song by SomeKindaWonderful * REVERSE art gallery, in Brooklyn, NY, US *Reverse tape effects including backmasking, the recording of sound in reverse * '' Reversing: Secrets of Reverse Engineering'', a book by Eldad Eilam *''Tegami Bachi: REVERSE'', the second season of the ''Tegami Bachi'' anime series, 2010 Driving * Reverse gear, in a motor or mechanical transmission * Reversing (vehicle maneuver), reversing the direction of a vehicle * Turning a vehicle through 180 degrees Sports and games *Reverse (American football), a trick play in American football *Reverse swing, a cricket delivery *Reverse (bridge), a type of bid in contract bridge Technology *Revers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfolobus Solfataricus
''Saccharolobus solfataricus'' is a species of thermophilic archaeon. It was transferred from the genus ''Sulfolobus'' to the new genus ''Saccharolobus'' with the description of Saccharolobus caldissimus in 2018. It was first isolated and discovered in the Solfatara volcano (which it was subsequently named after) in 1980 by two Germans microbiologists Karl Setter and Wolfram Zillig, in Solfatara volcano (Pisciarelli-Campania, Italy). However, these organisms are not isolated to volcanoes but are found all over the world in places such as hot springs. The species grows best in temperatures around 80° Celsius, a pH level between 2 and 4, and enough sulfur for ''solfataricus'' to metabolize in order to gain energy. These conditions qualify it as an extremophile and it is specifically known as a thermoacidophile because of its preference to high temperatures and low pH levels and it is also in aerobic and heterotropic categories for its metabolic system. It usually has a spherical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
