![]() Several EGSs derived from natural tRNA sequences have been shown to be effective in blocking gene expression in bacteria and mammalian cells. The other is the interaction between a target mRNA and the other domains of an EGS, which are required for folding of the RNase P-recognizable tertiary structure. One is the Watson-Crick base-pairing interaction between the anti-sense domain of an EGS and the accessible region of a target mRNA. Moreover two types of interaction govern the targeting specificity of EGS. Compared with other nucleic-acid-based gene-interference strategies, such as the RNAi approach that induces the cellular RISC RNase to cleave a target mRNA, targeted cleavage of mRNA by RNase P using an EGS is a unique approach that can be used to inactivate any RNA of known sequence expressed in vivo. Each technology has advantages and limitations in terms of targeting efficacy and specificity. Nucleic-acid-based gene-interference strategies, such as anti-sense oligonucleotides, ribozymes, and RNAi, are powerful research tools and promising therapeutic agents for human diseases. Subsequent studies have shown that EGS technology can be used to down-regulate gene expression in many organisms, such as bacteria, mammalian cells and maize cells. In principle, an mRNA sequence can be targeted for RNase P cleavage by hybridization with EGS to direct RNase P to the cleavage site. One of the two RNA molecules that resemble the complex is termed the external guide sequence (EGS). Accordingly, any complex of two RNA molecules that resembles a similar tRNA molecule can be recognized and cleaved by RNase P. One of the unique features of RNase P is its ability to recognize the structures, rather than the sequences, of tRNAs this allows the enzyme to cleave other substrates with similar structure to the tRNA precursor. This enzyme is found in cells from all three domains of life: the Bacteria, Eukaryote and Archaea. RNase P catalyzes the maturation of 5'-termini of all tRNAs by a single endonucleolytic cleavage of their precursors. These observations are potentially of great importance to further our understanding and use of C. The EGS library is a research tool for reverse genetic screening in C. ConclusionĮGS technology can be used to down-regulate gene expression in C. Of these, EGS-35 and EGS-83 caused the greatest phenotype changes, and their target mRNAs were identified as ZK858.7 mRNA and Lin-13 mRNA, respectively. About 6% of these EGSs induced abnormal phenotypes such as P0 slow postembryonic growth, P0 larval arrest, P0 larval lethality and P0 sterility. ![]() A subset of EGSs was randomly chosen for screening in the C. Examination of the composition of the EGS library showed that there was no obvious bias in the cloning of certain EGSs. We further generated an EGS library that contains a randomized antisense domain of tRNA-derived EGS ("3/4 EGS"). Consequently, the expression levels of Ngfp-lacZ and Mtgfp were affected by EGS-Ngfp-lacZ and EGS-Mtgfp, respectively. elegans strain PD4251, which contains Ngfp-lacZ and Mtgfp. These EGSs were introduced, both separately and together, into the C. elegans), we generated EGS-Ngfp-lacZ and EGS-Mtgfp that are targeted against Ngfp-lacZ and Mtgfp mRNA, respectively. To examine whether EGS technology can be used to down-regulate gene expression in Caenorhabditis elegans ( C. A method for inhibiting the expression of particular genes using external guide sequences (EGSs) has been developed in bacteria, mammalian cells and maize cells. ![]()
0 Comments
Leave a Reply. |