The application of a monster?
In this project, we have developed a simple approach to obtain Z-B chimeras under physiological conditions. Without special conditions such as high salt concentrations and base-modification, the product may possess biological activity. In other words, it will be capable of replication and transcription in vivo, and we have achieved these in vitro. As we all know, the negative supercoiled DNA that appears while transcription tends to form Z-DNA[1,3,5]. Today, we finally can observe the similar phenomenon. Also, with AFM and XRSD (x-ray single crystal diffraction), it will promote the research on Z-DNA structure. What’s more, we only prepared circular DNA with limited lengths (42, 53, 63, 74 and 84 bp). They are short, but chimera will grow, and research will continue. In the future, it may be hundreds of base pairs long, even become a whole plasmid. In short, it has great potential.
siRNA that is hard to degrade
As is known to all, the application of siRNA is restricted by its instability. We suspect that there may be Z–RNA if we replace the DNA chimera with RNA. With this research, we may design a RNA chimera, the Z part of which contains the siRNA sequences. While the Z-RNA can’t be recognized and degraded by enzyme, the A-RNA will be cut and the siRNA will be released. After release, without the constrain of circle, siRNA will transform from Z-RNA to A-RNA, and restore physiological activity. That is to say, we may be capable of producing a new kind of siRNA which has better stability and use ratio. As a result, siRNA chimera will have a great prospect in biology field and medicine field.
The chimera plasmid
Plasmid has certain base composition. For example, the 10% length of F1 factor contains the 90% of its C/G. It can be deduced that the plasmid also may be made into Z-B chimera. With the restriction enzyme, we can cut the plasmid to dsDNA, and use PCR to clone two kinds of ssDNA. Then we can obtain two kinds of ssDNA circle using the splint and DNA ligase. Finally, mix them up, heat to denature them and cool down. If all goes well, we will get the plasmid chimera. The target gene in the Z conformation part will avoid the risk of being cut by the enzyme in host cell. We can arrange the ori and promoter in the B part, so that they will keep biological activity. This plasmid can work like other plasmids, and is less likely to be degraded. For its linking number is 0, it can achieve replication and transcription without the help of topoisomerase, and we haven’t know what effect it will have on the host cell, but this would indeed be very interesting.
- Alexander Rich and Shuguang Zhang, Z-DNA: The Long Road to Biological Function, Nature, 2003, 4 (July): 566–72.
- Aliabadi, Hamidreza Montazeri, Parvin Mahdipoor, Cezary Kucharsky, Nicole Chan, and Hasan Uluda, Effect of siRNA Pre-Exposure on Subsequent Response to siRNA Therapy, Pharm Res (2015) 32:3813–3826.
- Response to siRNA Therapy, Pharm Res (2015) 32:3813–3826.
- Stephen Neidle, Principles of Nucleic Acid Structure, 2008
- 陈小英, 质粒的基本特征和分类, 综述.
- 王镜岩, 朱胜庚, 徐长法, 生物化学, 第三版, 北京:高等教育出版社, 2002.