Fanzor

The Fanzor (Fz) protein is an eukaryotic, RNA-guided DNA endonuclease, which means it is a type of DNA cutting enzyme that uses RNA to target genes of interest. It has been recently discovered and explored in a number of studies.<ref name="saito" /><ref name="Awan" /><ref name="Bao" /> In bacteria, RNA-guided DNA endonuclease systems, such as the CRISPR/Cas system, serve as an immune system to prevent infection by cutting viral genetic material.<ref name="Badon" /> Currently, CRISPR/Cas9-mediated’s DNA cleavage has extensive application in biological research, and wide-reaching medical potential in human gene editing.<ref name="Badon" />

Fanzor belongs to the OMEGA system.<ref name="saito" /><ref name="Awan" /><ref name="Badon" /> Evolutionarily, it shares a common ancestor, OMEGA TnpB, with the CRISPR/Cas12 system.<ref name="saito" /><ref name="Yang" /> Due to the shared ancestry between the OMEGA system and the CRISPR system, the protein structure and DNA cleavage function of Fanzor and Cas12 remain largely conserved.<ref name="saito" /><ref name="Jiang" /> Combined with the widespread presence of Fanzor across the diverse genomes of different eukaryotic species,<ref name="Jiang" /> this raises the possibility of OMEGA Fanzor being an alternative to CRISPR/Cas system with better efficiency and compatibility in other complex eukaryotic organisms, such as mammals.

Fanzor functions as a potential human genome editor

Due to its eukaryotic origin, the OMEGA Fanzor system may have some advantages over the better studied CRISPR/Cas gene editor in terms of human genome editing applications.<ref name="saito" /> In a CRISPR/Cas9 system, Cas9 proteins are guided by the guide RNA (gRNA) and protospacer adjacent motif (PAM) for DNA cleavage. Interestingly, Fanzor genes in the soil fungus S. punctatus <ref name="saito" /><ref name="Yang" /> also contain non-coding sequences called ωRNA. Similar to CRISPR/Cas9, Fanzor protein is shown to cleave DNA in test tubes under the guidance of ωRNA and Target-adjacent motif (TAM).<ref name="saito" />

As shown in the schematic, Cas9 DNA cleavage is instructed by the gRNA and the PAM sequence “NGG”<ref name="Anders"/> on the target DNA, where N can be any of the four DNA components (A, G, C or T). Similarly, Fanzor DNA cleavage is instructed by the ωRNA and the TAM sequence “CATA” on the target DNA1. Not an accurate representation of size and structure of the RNAs and proteins. (created using Biorender)

In human cells, the Fanzor protein of Spizellomyces punctatus was successfully tested and shown to cleave DNA effectively.<ref name="saito" /> However, its efficiency is lower compared to the closely related CRISPR/Cas12a system.<ref name="saito" /> By modifying and tweaking the ωRNA and the amino acid sequence, a second version of the S. punctatus Fanzor protein with improved cleavage efficiency - comparable to that of the CRISPR/Cas12a system - was engineered.<ref name="saito" /> This shows that, with better modifications and more research, OMEGA Fanzor has the potential to match the CRISPR system in human genome editing in the future.

Clinical and Biotechnological Significance

Studies conclude that Fanzor has great potential for efficient human genome editing<ref name="saito" /><ref name="Jiang" /> with a higher chance of not getting attacked by the immune system.<ref name="Jiang" /> For example, Fanzor could be used in personalized cancer treatments where the patient’s own T-cells - important cells of the immune system that recognize and fight foreign pathogens - are edited in order to recognize and destroy cancer cells.<ref name="Awan" /><ref name="Dimitri" /> In the field of regenerative medicine, it offers hope for an application in stem cell therapy to treat many disease of genetic origin like type 1 diabetes or neurodegenerative diseases.<ref name="Awan" />

Furthermore, Fanzor could potentially be used for genome editing in eggs and sperm<ref name="Awan" /> for disease prevention and infertility treatment. However, the intervention in such cells’ DNA comes with risks and requires strict ethical guidelines.<ref name="Rubeis" />

One major advantage of Fanzor in comparison to the CRISPR/Cas9 system is its small size. Therefore, it can be delivered with viral vectors, which are modified dead bodies of viruses engineered to safely deliver genetic material, such as adenoviruses.<ref name="Badon" /> Adenoviruses are commonly used in medical applications like gene deliveries or vaccines<ref name="Lee" /> that do not elicit immune responses within the human body.<ref name="Badon" />

However, researchers caution that further research is necessary to improve the editing efficiency<ref name="saito"/><ref name="Jiang" /> and precision.<ref name="saito"/>

Next to the application in human cells, Fanzor is a prospective tool for specific genome editing in plants, because of the aforementioned advantages of the protein being a small size.<ref name="Awan" /> Thereby, the nutrient content, the resistance to diseases and the affordability of crops could be improved.<ref name="Pixley" /> Moreover, in regard to the current and arising challenges caused by climate change, crops could be adjusted to better endure stress factors such as drought, salinity and increasing temperatures.<ref name="Karavolias" />