Zinc refers to KERNs.

related topics .Zinc refers to
inuclease
nuclease
(ZFN) consisting of a
DNA
recognition domain and a nonse specific
nucleic acid
endoenzyme. The DNA identification domain is made up of a series of Cys2-His2 zinc finger proteins (typically 3 to 4) in series, each of which identifies and binds to a specific triple base. Zinc refers to proteins derived from the transcriptional regulatory factor family, which is widely found in ceuterous organisms from
yeast
to humans, forming alpha-beta-beta secondary structures. The 16 amino acids
alpha
determine the DNA binding specificity of zinc fingers and the skeleton structure is conservative. Changes to the amino acid introduction sequence that determine DNA binding specificity can result in new DNA binding specificity.has now been published that highly specific zinc finger proteins screened from nature and artificially mutated can identify all GNNs and ANNs as well as some CNN and TNN triplets. Multiple zinc finger proteins can be formed in series to form a zinc finger protein group to identify a specific base sequence, with strong specificity and plasticity, very suitable for the design of ZFNs. THE DNA shear domain consisting of 96 amino acid residues from the C end of FokI (Kim et al., 1996). FokI is a
-restrictive endoenzyme
from the seabed, which has enzymatic cutting activity only in the djumer state (Kim et al., 1994), and each FokI monomer is connected to a zinc finger proteome to form a ZFN, identifying specific bits, and generating an enzyme-cutting enzyme when the two identification points are at an appropriate distance (6 to 8 bp) and two monomer ZN interactions. In order to achieve the purpose of DNA fixed-point cutting.the technology has long been monopolized by Sangamo Bio, which only cooperates with some research institutions. Now that's changed, an association of eight laboratories,
in molecular biology
J. Led by Keith Joung, an open source approach to ZNF (Maeder et al., 2008) was proposed. The
has
66 "zinc finger" libraries, selectively targeting different DNA sequences. The "zinc finger nuclease" built from the library is about 1-50% efficient in testing a
plantgene
and three human genes, which can be comparable to Sangamo, classical gene legislation.a DNA-targeting technique that requires a high degree of specificity if applied to actual scientific research or medicine, i.e. avoiding the wrong off-target. In fact, however, the accuracy of DNA shearing is not as strong as expected due to the mechanism of ZNF shearing: DNA shearing requires the two FokI cutting areas to be polylyzed and at least one unit to bind DNA. Because the process of djuarization is independent of DNA shearing, the formation of isodes, and the formation of two units of ionosomes, can also cause DNA shearing, and they have different identification sequences. It is conceivable that ZNF, in the form of a less specific omogeneic domogene, will cut the false echo sequence in the genome. Moreover, under certain conditions, a single ZNF unit combined with DNA (the identification sequence is only 9 to 12 bp) can also cause DNA shearing. Thus, two different ZNF units may produce a total of seven different identification sequences of endoenzymes. These nonsexual behaviors can be ZNF toxic..Miller et al. and Szczeoek et al. (2007) improved this technology, respectively. They built a series of FokI enzymes that favour isodes. By examining FokI's crystal structure, both groups mutated the amino acids on the two alpha helixes combined by the two units of the mediator enzyme to reduce the formation of ionospheric binds: the researchers built a pair of asymmetric interfaces. Although off-target appearance has decreased significantly, it is still inevitable that individual ZNF units will bind to DNA when enzymatic cutting occurs, and perhaps further development will require the complete destruction of FokI's ability to bind DNA..ZFNs have been used to enhance the cogeneration of african claw eggs, worms, fruit flies and zebrafish cells (Bibikova et al., 2001; Morton et al., 2006; Meng et al, 2008; Doyon et al., 2008). In fruit flies, ZFNs-mediated iso-recombination frequency is considerable, sometimes more than 1% of children have ionized recombination-mediated gene targeting events (Beumer et al., 2006). In zebrafish, 30%-50% of individuals pass on ZFN-induced mutations to their children, while 7% to 18% of subgenres are mutants. SoleXA sequencing showed that in normal embryos, off-targeting was only 1%. On plants, Lloyd and others (2005) induced a fixed mutation of the chromosome gene with ZFN in the abyss mustard, with a mutation rate of up to 20% in offspring. Voytas' team has shown that ZFNs can improve the frequency of plant gene spot integration and replacement. In the experiment, they designed a target gene GUS: NPTII, which is missing 600bp, and converted the tobacco protosome together with the 600 bp iso-DNA fragment and ZFNs instantaneous expression vector, and 10% of the converted cells received a fixed-point replacement of the gene, which was 104 to 105 times more efficient than without ZFNs. Molecular testing showed that 20% of recombination events were accurate and did not accompany the absence or insertion of the base (Wright et al., 2005). The results show that using ZFNs fixed-point cutting chromosomal DNA can significantly improve the efficiency of gene fixed-point integration mediated by combination, which provides a very promising tool for gene fixed-point integration and replacement..ZNF technology also has potential clinical applications. There are two main ways of traditional gene therapy, one is to use viruses to carry a complete sequence of genes into the human body or inject a small piece of the correct DNA sequence to correct errors or make the wrong genes do not behave, but so far, in fact, scientists have not been able to confirm that these methods are practically efficient and safe. The principle of ion exchange makes it possible for cells to correct the wrong DNA sequence on their own is the most basic principle in the development of gene therapy. This process is done in two separate steps: first, a double-stranded fracture is introduced into the DNA to initiate the cell's own repair system, and then a similar sequence introduced by the "same-origin recombination" reference is used as a template to repair the gene, thus achieving base replacement at the specified site..Urnov et al. (2005) A four-finger ZFN was designed for severe immunodeficiration (X-linked severe combined immune deficiency (SCID)) caused by a mutation in an IL2R gene. SCID causes T cells to lose their ability to fight invasion and infection from the outside world, and scientists combine the right DNA fragments and ZFN to process these SCID T cells in
cultured
dishes. The system is used to mediate the efficient repair of human cell IL2R. In the non-selective pressure repair efficiency of 15% to 18%, and in the body, the modified cells than the original mutant cells have a selective advantage, so such repair efficiency is sufficient for gene therapy. Such an operation has a clear advantage over traditional technologies such as retrovirus: it does not create the risk of unwanted genetic recombination because it corrects the wrong sequence rather than adding a correct copy. This offers hope for gene repair using ZFN.but ZNF technology has a long way to go for clinical treatment. For example, one cannot expect the introduction of ZNF protein to cause an attack on the immune system. And so far, at least, such techniques seem to be used only for cells that can be extracted from the patient's body, operated on them in vitro, and injected back into the patient's body: the efficiency of injecting genes directly into the body is too low. Finally, the accuracy of ZNF operation within the cell must also be carefully assessed: very few errors can also lead to serious consequences such as cell carcinoma.
.