Epigenetic Reprogramming in Early Embryo Development
Cristina Camprubí, Joan Blanco in Epigenetics and Assisted Reproduction, 2018
In eukaryotes, two main types of TEs have been described, retrotransposons and DNA transposons. DNA transposons or class II TEs move by a simple “cut and paste” mechanism: A DNA transposon sequence is removed from one genomic location and inserted in a new genomic site, using a specialized protein termed transposase (67). Its proportion in the human and mouse genome is lower than 5%, and no active DNA-transposons are present in these genomes at present. On the other hand, retrotransposons, or class I TEs, move by a “copy and paste” mechanism of mobilization that requires reverse transcription of an intermediate TEs RNA. In the human and mouse, more than 95% of TEs belong to this class (66) and represent more than 35% of the genome (68).
Mobile DNA Sequences and Their Possible Role in Evolution
S. K. Dutta in DNA Systematics, 2019
One can conclude from this section that many different elements can play the role of passive transposons, mobilized either by transposase or by reverse transcriptase. For the first type of transposition, the inverted repeats are important. For the second type, the transcription of the element (existence of promoter) and the presence of a sequence appropriate for reverse transcriptase primer binding are required.
The potential of gene therapy for mucopolysaccharidosis type I
Published in Expert Opinion on Orphan Drugs, 2020
Luisa Natalia Pimentel Vera, Guilherme Baldo
Other strategies were attempted in parallel throughout the years, as alternatives to viral vectors. Non-viral vectors avoid immunogenicity and also have lower cost of production. Sleeping beauty transposon (SBT) is a non-viral vector that combines some advantages of viruses (capacity of integration) without the need of a viral particle [60]. It is composed of a transposomic region, which is replaced by the transgene to be expressed and a transposase, that generates double-stranded breaks in the DNA and allow the insertion of the transgene [61]. Among its advantages is the fact of (i) not relying on an endogenous DNA repair machinery to integrate into the genome, (ii) the system is not restricted to a cell cycle phase, so it is possible to reach and transpose a wide range of cell types including those with high therapeutic potential and (iii) it allows stable and efficient transgene production once transposed [62,63].
Porphyromonas gingivalis and its CRISPR-Cas system
Published in Journal of Oral Microbiology, 2019
Transposase is an enzyme that binds to the two ends of a transposon and bring them together to form a loop. It then catalyzes movement of the transposon to another part of the genome by a cut and paste mechanism or replicative transposition. In the study by Chen et al. [23] who did comparative genomics of 19 P. gingivalis strains, a high prevalence of transposase proteins was found encoded in P. gingivalis (Table 2); actually as much as 149 copies in strain A7436. In another study transposases were found in all of the 35 genomes of P. gingivalis examined, varying in number from 8 (strains Ando, F0185, SDJ5) to 103 (A7436) [28]. The lower number of transposases detected in the original genomes that were not completely sequenced in this study was most likely due to the in-between-contig sequence gaps that may contain highly repeated sequences such as transposases and IS elements. The completed genome with the lowest number of mobility-related genes was that of strain A7A1-28, where 68 transposases were detected.
Transposon mutagenesis in oral streptococcus
Published in Journal of Oral Microbiology, 2022
Yixin Zhang, Zhengyi Li, Xin Xu, Xian Peng
Transposons are mobile genetic factors that can move within genomes through ‘cut and paste’ or copy mechanisms. A transposase encoded by a transposon can recognise specific inverted repeat sequences at both ends of the transposon, separate the transposon from adjacent sequences, and insert it into a DNA target site [31]. The most common application of transposons is insertional mutagenesis, which can be used to create libraries of mutant strains. The success of transposon mutant library screening depends on the number of mutants screened and diversity of the library.
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