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RecBCD
Exodeoxyribonuclease V (EC 3.1.11.5, RecBCD, Exonuclease V, ''Escherichia coli'' exonuclease V, ''E. coli'' exonuclease V, gene recBC endoenzyme, RecBC deoxyribonuclease, gene recBC DNase, gene recBCD enzymes) is an enzyme of ''E. coli'' that initiates recombinational repair from potentially lethal double strand breaks in DNA which may result from ionizing radiation, replication errors, endonucleases, oxidative damage, and a host of other factors. The RecBCD enzyme is both a helicase that unwinds, or separates the strands of DNA, and a nuclease that makes single-stranded nicks in DNA. It catalyses exonucleolytic cleavage (in the presence of ATP) in either 5′- to 3′- or 3′- to 5′-direction to yield 5′-phosphooligonucleotides. Structure The enzyme complex is composed of three different subunits called RecB, RecC, and RecD and hence the complex is named RecBCD (Figure 1). Before the discovery of the ''recD'' gene, the enzyme was known as “RecBC.” Each subunit is en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homologous Recombination
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in Cell (biology), cellular organisms but may be also RNA in viruses). Homologous recombination is widely used by cells to accurately DNA repair, repair harmful DNA breaks that occur on both strands of DNA, known as double-strand breaks (DSB), in a process called homologous recombinational repair (HRR). Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and ovum, egg cells in animals. These new combinations of DNA represent genetic variation in offspring, which in turn enables populations to Adaptation, adapt during the course of evolution. Homologous recombination is also used in horizontal gene transfer to exchange genetic material between different strains and species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chi Site
A Chi site or Chi sequence is a short stretch of DNA in the genome of a bacterium near which homologous recombination is more likely to occur than on average across the genome. Chi sites serve as stimulators of DNA double-strand break repair in bacteria, which can arise from radiation or chemical treatments, or result from replication fork breakage during DNA replication. The sequence of the Chi site is unique to each group of closely related organisms; in '' E. coli'' and other enteric bacteria, such as Salmonella, the core sequence is 5'-GCTGGTGG- 3' plus important nucleotides about 4 to 7 nucleotides to the 3' side of the core sequence. The existence of Chi sites was originally discovered in the genome of bacteriophage lambda, a virus that infects ''E. coli'', but is now known to occur about 1000 times in the ''E. coli'' genome. The Chi sequence serves as a signal to the RecBCD helicase-nuclease that triggers a major change in the activities of this enzyme. Upon encountering th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holliday Junction
A Holliday junction is a branched nucleic acid structure that contains four double-stranded arms joined. These arms may adopt one of several conformations depending on buffer salt concentrations and the sequence of nucleobases closest to the junction. The structure is named after Robin Holliday, the molecular biologist who proposed its existence in 1964. In biology, Holliday junctions are a key intermediate in many types of genetic recombination, as well as in double-strand break repair. These junctions usually have a symmetrical sequence and are thus mobile, meaning that the four individual arms may slide through the junction in a specific pattern that largely preserves base pairing. Additionally, four-arm junctions similar to Holliday junctions appear in some functional RNA molecules. Immobile Holliday junctions, with asymmetrical sequences that lock the strands in a specific position, were artificially created by scientists to study their structure as a model for natura ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RuvABC
RuvABC is a complex of three proteins that mediate branch migration and resolve the Holliday junction created during homologous recombination in bacteria. As such, RuvABC is critical to bacterial DNA repair. RuvA and RuvB bind to the four strand DNA structure formed in the Holliday junction intermediate, and migrate the strands through each other, using a putative spooling mechanism. The RuvAB complex can carry out DNA helicase activity, which helps unwind the duplex DNA. The binding of the RuvC protein to the RuvAB complex is thought to cleave the DNA strands, thereby resolving the Holliday junction. Protein complex The RuvABC is a complex of three proteins that resolve the Holliday junction formed during bacterial homologous recombination. In ''Escherichia coli'', DNA replication forks stall at least once per cell cycle, so that DNA replication must be restarted if the cell is to survive. Replication restart is a multi-step process in ''E. coli'' that requires the sequential ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Repair
DNA repair is a collection of processes by which a cell (biology), cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer. DNA is constantly modified in Cell (biology), cells, by internal metabolism, metabolic by-products, and by external ionizing radiation, ultraviolet light, and medicines, resulting in spontaneous DNA damage involving tens of thousands of individual molecular lesions per cell per day. DNA modifications can also be programmed. Molecular lesions can cause structural damage to the DNA molecule, and can alter or eliminate the cell's ability for Transcription (biology), transcription and gene expression. Other lesions may induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells following mitosis. Consequently, DNA repair as part of the DNA damage response (DDR) is constantly active. When normal repair proce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endonuclease
In molecular biology, endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain (namely DNA or RNA). Some, such as deoxyribonuclease I, cut DNA relatively nonspecifically (with regard to sequence), while many, typically called '' restriction endonucleases'' or ''restriction enzymes'', cleave only at very specific nucleotide sequences. Endonucleases differ from exonucleases, which cleave the ends of recognition sequences instead of the middle (''endo'') portion. Some enzymes known as "exo-endonucleases", however, are not limited to either nuclease function, displaying qualities that are both endo- and exo-like. Evidence suggests that endonuclease activity experiences a lag compared to exonuclease activity. Restriction enzymes are endonucleases from eubacteria and archaea that recognize a specific DNA sequence. The nucleotide sequence recognized for cleavage by a restriction enzyme is called the ''restriction site''. Typically, a restriction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escherichia Coli
''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly found in the lower intestine of warm-blooded organisms. Most ''E. coli'' strains are part of the normal microbiota of the gut, where they constitute about 0.1%, along with other facultative anaerobes. These bacteria are mostly harmless or even beneficial to humans. For example, some strains of ''E. coli'' benefit their hosts by producing vitamin K2 or by preventing the colonization of the intestine by harmful pathogenic bacteria. These mutually beneficial relationships between ''E. coli'' and humans are a type of mutualistic biological relationship—where both the humans and the ''E. coli'' are benefitting each other. ''E. coli'' is expelled into the environment within fecal matter. The bacterium grows massi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EC 3
EC3 can refer to: People * Ethan Carter III (EC3) (born 1983), American professional wrestler Places * EC3, a district in the London EC postcode area Groups, organizations, companies * European Cybercrime Centre * EarthCheck, formerly EC3 Global; international tourism advisory group Transportation * BJEV ''EC3'', a Chinese electric vehicle * KUR ''EC3 class'', a class of steam locomotive * EC-3 radar, Italian WWII radar Other uses * Dolby Digital Plus, also known as EC-3 * Hydrolase enzymes (EC 3); see List of EC numbers (EC 3) See also * ECCC (other) {{Letter-NumberCombDisambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-molecule FRET
Single-molecule fluorescence (or Förster) resonance energy transfer (or smFRET) is a Biophysics, biophysical Outline of biophysics#Biophysical techniques, technique used to measure distances at the 1-10 nanometer scale in single molecules, typically biomolecules. It is an application of Förster resonance energy transfer, FRET wherein a pair of donor and acceptor fluorophores are excited and detected at a single molecule level. In contrast to "ensemble FRET" which provides the FRET signal of a high number of molecules, single-molecule FRET is able to resolve the FRET signal of each individual molecule. The variation of the smFRET signal is useful to reveal kinetic information that an ensemble measurement cannot provide, especially when the system is under equilibrium with no ensemble/bulk signal change. Heterogeneity among different molecules can also be observed. This method has been applied in many measurements of intramolecular dynamics such as DNA/RNA/protein folding/unfolding an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillus Subtilis
''Bacillus subtilis'' (), known also as the hay bacillus or grass bacillus, is a gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacillus'', ''B. subtilis'' is rod-shaped, and can form a tough, protective endospore, allowing it to tolerate extreme environmental conditions. ''B. subtilis'' has historically been classified as an obligate aerobe, though evidence exists that it is a facultative anaerobe. ''B. subtilis'' is considered the best studied Gram-positive bacterium and a model organism to study bacterial chromosome replication and cell differentiation. It is one of the bacterial champions in secreted enzyme production and used on an industrial scale by biotechnology companies. Description ''Bacillus subtilis'' is a Gram-positive bacterium, rod-shaped and catalase-positive. It was originally named ''Vibrio subtilis'' by Christian Gottfried Ehrenberg, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
