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ATP-dependent Chromatin Remodeling
Chromatin remodeling is the dynamic modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression. Such remodeling is principally carried out by 1) covalent histone modifications by specific enzymes, e.g., histone acetyltransferases (HATs), deacetylases, methyltransferases, and kinases, and 2) ATP-dependent chromatin remodeling complexes which either move, eject or restructure nucleosomes. Besides actively regulating gene expression, dynamic remodeling of chromatin imparts an epigenetic regulatory role in several key biological processes, egg cells DNA replication and repair; apoptosis; chromosome segregation as well as development and pluripotency. Aberrations in chromatin remodeling proteins are found to be associated with human diseases, including cancer. Targeting chromatin remodeling pathways is currently evolving as a major therapeutic strategy in the treatment of several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in reinforcing the DNA during cell division, preventing DNA damage, and regulating gene expression and DNA replication. During mitosis and meiosis, chromatin facilitates proper segregation of the chromosomes in anaphase; the characteristic shapes of chromosomes visible during this stage are the result of DNA being coiled into highly condensed chromatin. The primary protein components of chromatin are histones. An octamer of two sets of four histone cores (Histone H2A, Histone H2B, Histone H3, and Histone H4) bind to DNA and function as "anchors" around which the strands are wound.Maeshima, K., Ide, S., & Babokhov, M. (2019). Dynamic chromatin organization without the 30-nm fiber. ''Current opinion in cell biology, 58,'' 95–104. https://doi.o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Methylation
DNA methylation is a biological process by which methyl groups are added to the DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts to repress gene transcription. In mammals, DNA methylation is essential for normal development and is associated with a number of key processes including genomic imprinting, X-chromosome inactivation, repression of transposable elements, aging, and carcinogenesis. As of 2016, two nucleobases have been found on which natural, enzymatic DNA methylation takes place: adenine and cytosine. The modified bases are N6-methyladenineD. B. Dunn, J. D. Smith: ''The occurrence of 6-methylaminopurine in deoxyribonucleic acids.'' In: ''Biochem J.'' 68(4), Apr 1958, S. 627–636. PMID 13522672. ., 5-methylcytosineB. F. Vanyushin, S. G. Tkacheva, A. N. Belozersky: ''Rare bases in animal DNA.'' In: ''Nature.'' 225, 1970, S. 948–949. PMID 4391887. and N4- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luong LD SA F2
Liang (Romanization used in China, ) is an East Asian surname of Chinese origin. The surname is often transliterated as Leung (in Hong Kong) or Leong (in Macau, Hong Kong, Malaysia, Singapore, and the Philippines) according to its Cantonese and Hakka pronunciation, Neo / Nio / Niu (Hokkien, Teochew, Hainan), or Liong (Foochow). In Indonesia, it is known as Liang or Nio. It is also common in Korea, where it is written Ryang (량) or Yang (양). In Vietnam, it's pronounced as Lương. It is listed 128th in the classic text Hundred Family Surnames. In 2019 it was the 22nd most common surname in Mainland China. In comparison, it is the 7th most common surname in Hong Kong, where it is usually written Leung or Leong. History During the reign of the Zhou dynasty King Xuan of Zhou (827–782 bc), Qin Zhong set out on an expedition to subdue the peoples to the west in Central Asia. After Qin Zhong died, the King divided the area of Shang among them, the second son of Qin Zhong recei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bromodomain
A bromodomain is an approximately 110 amino acid protein domain that recognizes acetylated lysine residues, such as those on the ''N''-terminal tails of histones. Bromodomains, as the "readers" of lysine acetylation, are responsible in transducing the signal carried by acetylated lysine residues and translating it into various normal or abnormal phenotypes. Their affinity is higher for regions where multiple acetylation sites exist in proximity. This recognition is often a prerequisite for protein-histone association and chromatin remodeling. The domain itself adopts an all-α protein fold, a bundle of four alpha helices each separated by loop regions of variable lengths that form a hydrophobic pocket that recognizes the acetyl lysine. Discovery The bromodomain was identified as a novel structural motif by John W. Tamkun and colleagues studying the drosophila gene ''Brahma''/''brm'', and showed sequence similarity to genes involved in transcriptional activation. The name "bromo ... [...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] |
Chromodomain Helicase DNA-binding (CHD) Protein Subfamily
Chromodomain helicase DNA-binding (CHD) proteins is a subfamily of ATP-dependent chromatin remodeling complexes (remodelers). All remodelers fall under the umbrella of RNA/DNA helicase superfamily 2. In yeast, CHD complexes are primarily responsible for nucleosome assembly and organization. These complexes play an additional role in multicellular eukaryotes, assisting in chromatin access and nucleosome editing. Functions of CHD subfamily proteins Similar to the imitation switch (ISWI) subfamily of ATP-dependent chromatin remodelers, CHD complexes regulate the assembly and organization of mature nucleosomes along the DNA. Histones are removed during DNA replication; following behind the replisome, histones start to assemble as immature pre-nucleosomes on nascent DNA. With the help of CHD complexes, histone octamers can mature into native nucleosomes. Following nucleosome formation, CHD complexes organize nucleosomes by regularly spacing them apart along the DNA. Additionally, CHDs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mi-2/NuRD Complex
In the field of molecular biology, the Mi-2/NuRD (Nucleosome Remodeling Deacetylase) complex, is a group of associated proteins with both ATP-dependent chromatin remodeling and histone deacetylase activities. , Mi-2/NuRD was the only known protein complex that couples chromatin remodeling ATPase and chromatin deacetylation enzymatic functions. The NuRD complex contains seven subunits: the histone deacetylase core proteins HDAC1 and HDAC2, the histone-binding proteins RbAp46 and RbAp48, the metastasis-associated proteins MTA1 (or MTA2 / MTA3), the methyl-CpG-binding domain protein MBD3 (or MBD2) and the chromodomain-helicase-DNA-binding protein CHD3 (aka Mi-2alpha) or CHD4 (aka Mi-2beta). The histone deacetylases HDAC1 and HDAC2 and the histone binding proteins RbAp48 and RbAp46 form a core complex shared between NuRD and Sin3-histone deacetylase complexes. Overexpression of Mbd3, a subunit of NuRD, inhibits induction of iPSCs. Depletion of Mbd3, on the other hand, improves rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISWI
ISWI or imitation SWI is a protein found in the common fruit fly. It is the first ATPase protein subunit, subunit which has been isolated in the ISWI chromatin chromatin remodeling, remodeling family. This protein presents high level of similarity to the SWI/SNF chromatin remodeling family in the ATPase domain. Outside the ATPase domain ISWI loses the similarity with the member of the SWI/SNF family, possessing a SANT domain instead of the bromodomain. The protein ISWI can interact with several proteins giving three different chromatin-remodeling complexes in ''Drosophila melanogaster'': Nucleosome remodeling factor, NURF (nucleosome remodeling factor), CHRAC (chromatin remodeling and assembly complex) and ACF (ATP-utilising chromatin remodeling and assembly factor). ''In vitro'', the ISWI protein alone can assemble nucleosomes on linear DNA and it can move nucleosomes on linear DNA from the center to the extremities. Inside the CHRAC complex, ISWI catalyzes the inverse reaction, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SWI/SNF
In molecular biology, SWI/SNF (SWItch/Sucrose Non-Fermentable), is a subfamily of ATP-dependent chromatin remodeling complexes, which is found in eukaryotes. In other words, it is a group of proteins that associate to remodel the way DNA is packaged. This complex is composed of several proteins – products of the SWI and SNF genes (, /, , , ), as well as other polypeptides. It possesses a DNA-stimulated ATPase activity that can destabilize histone-DNA interactions in reconstituted nucleosomes in an ATP-dependent manner, though the exact nature of this structural change is unknown. The SWI/SNF subfamily provides crucial nucleosome rearrangement, which is seen as ejection and/or sliding. The movement of nucleosomes provides easier access to the chromatin, allowing genes to be activated or repressed. The human analogs of SWI/SNF are "BRG1- or BRM-associated factors", or BAF (SWI/SNF-A) and "Polybromo-associated BAF", which is also known as PBAF (SWI/SNF-B). There are also ''Drosop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Repression
In molecular genetics, a repressor is a DNA- or RNA-binding protein that inhibits the expression of one or more genes by binding to the operator or associated silencers. A DNA-binding repressor blocks the attachment of RNA polymerase to the promoter, thus preventing transcription of the genes into messenger RNA. An RNA-binding repressor binds to the mRNA and prevents translation of the mRNA into protein. This blocking or reducing of expression is called repression. Function If an inducer, a molecule that initiates the gene expression, is present, then it can interact with the repressor protein and detach it from the operator. RNA polymerase then can transcribe the message (expressing the gene). A co-repressor is a molecule that can bind to the repressor and make it bind to the operator tightly, which decreases transcription. A repressor that binds with a co-repressor is termed an ''aporepressor'' or ''inactive repressor''. One type of aporepressor is the trp repressor, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Activation
Regulation of gene expression, or gene regulation, includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA). Sophisticated programs of gene expression are widely observed in biology, for example to trigger developmental pathways, respond to environmental stimuli, or adapt to new food sources. Virtually any step of gene expression can be modulated, from transcriptional initiation, to RNA processing, and to the post-translational modification of a protein. Often, one gene regulator controls another, and so on, in a gene regulatory network. Gene regulation is essential for viruses, prokaryotes and eukaryotes as it increases the versatility and adaptability of an organism by allowing the cell to express protein when needed. Although as early as 1951, Barbara McClintock showed interaction between two genetic loci, Activator (''Ac'') and Dissociator (''Ds''), in the color formation of maize seeds, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
