The CRISPR-Cas system: its origin, functions and applications in biotechnology: A Review

Abstract

The CRISPR-Cas system is a genome editing system seen in prokaryotic immune system. Bacteria and archaea protect itself against invading viruses and plasmid by targeting RNA or DNA of the invading element predominantly using this gene-editing tool. The CRISPR- Cas defense mechanism is carried out in three stages; adaptation stage where the spacers are inserted into the CRISPR locus, the expression stage where crRNA is formed by transcription of the CRISPR loci and the interference stage where the invading element is destroyed by the crRNA and cas proteins. The CRISPR-cas has been involved in many other functions apart from the immune defense they include; DNA repair, regulation of virulence, genome evolution, inhibit biofilm formation etc. The application of CRISPR-Cas system include genome engineering, agriculture to efficiently target and mutate plants, improve crop yield and crop resistance, in medicine to eradicate genetic diseases. However, ethical considerations are a major setback of CRISPR-Cas application especially in medicine. CRISPR-Cas has been used in variety of species including cultured human cell, rice, drosophila and mice.