Genome Editing (also known as gene editing) is a group of techniques that enable scientists to modify (add, remove or alter) the DNA of an organism. It cuts specific sequences of DNA with enzymes called called “engineered nucleases”. The features of a cell or an organism may be modified by editing the genome (Song,2019).
By Lala Rukh khan & Warda Fatima (2020)
The three types of genome editing are small DNA changes, removal of DNA section and insertion of DNA section. In small DNA changes, a nuclease enzyme is engineered to cut a particular position in the DNA. After cutting, the cell’s normal DNA repair machinery will recognize the damage and join the two cut ends of DNA. This process is not perfect and a few bases are lost or added when DNA is repaired. In removal of DNA section, a nuclease enzyme is engineered to make cuts in the section that you want to remove. After that the DNA repair machinery will identify the damage, but can mistakenly link the wrong ends of DNA together. In insertion of DNA section, an enzyme cuts the DNA a changed piece of DNA identical in sequence to the site of the cut is inserted after the DNA has been cut to repair the break.
Genome editing works by using an enzyme “engineered nuclease”, which is made up of two types. One is the portion of the nuclease that cuts DNA and second is the DNA-targeting portion that is designed to direct the nuclease to a particular DNA sequence. The cell can repair the cut naturally after cutting the DNA in a particular place
There are total three discus worthy systems of genome editing. Genome contain all contain nuclease part to cut DNA and also DNA targeting part to recognize the DNA sequence which they cut. One of the discus worthy system is CRISPR (clustered regularly interspaced short palindromic repeats). This system is
- Cheap and efficient method.
- It is DNA target part and thus it consists of molecules of RNA and it is designed to bind specific DNA bases through complementary base pairing.
- Nuclease part that cuts DNA.
- It was discovered in bacteria and you can use this system to destroy invading types of viruses.
Second system is ZFNs (Zinc finger nuclease), in which,
- The DNA binding parts of zinc finger nuclease is made of their proteins which bind to about three DNA bases. Different combinations of zinc finger proteins can bind to different DNA sequencing it is although very hard to predict without testing them firstly.
- Its nuclease part is normally like Fok1 nuclease and it cuts DNA.
- Also, two Fok1 molecules come together so to make a cut in the DNA and thus a pair of zinc finger nuclease are made which means one binding to each strand.
Third system is TALENS: (Transcription activator like effector nucleases), in which,
- DNA binding domains are made of transcription activator like effector domain.
- Also, there are four types of different TALE domains one is for each DNA bases thus they can be engineered to bind specific DNA sequences easily then zinc finger nuclease.
- Like ZFNs, the nuclease part of TALENs is normally a Fok1 nuclease.
- Two kind of Fok1 molecules come together to make a cut in DNA so two TALENs are made it means that one is for each strand.
Genome editing can be used for biotechnology: In agriculture, genome editing has been used to genetically modify crops to increase their yields and resistance to disease and drought, as well as the cattle that do not have horns has been genetically modified. In order to understand their biology and how they function, genome editing may be used to modify the DNA in cells or organisms. Genome editing has been used to change human blood cells, which are then inserted back in the body to treat conditions such as leukemia and AIDS. Other diseases (such as MRSA) and simple hereditary disorders (such as muscular dystrophy and hemophilia) could also theoretically be treated with it.
Schulte-Merker, S., & Stainier, D. Y. (2014). Out with the old, in with the new: reassessing morpholino knockdowns in light of genome editing technology. Development, 141(16), 3103-3104.
Araki, M., Nojima, K., & Ishii, T. (2014). Caution required for handling genome editing technology. Trends in biotechnology, 32(5), 234-237.
Song, R., Zhai, Q., Sun, L., Huang, E., Zhang, Y., Zhu, Y., … & Lu, H. (2019). CRISPR/Cas9 genome editing technology in filamentous fungi: progress and perspective. Applied microbiology and biotechnology, 103(17), 6919-6932.
Authors Lala Rukh khan & Warda Fatima (2020) Department of biotechnology, Kinnaird college for womenLahore, Pakistan.