Relationship between structure and splicing of self-splicing introns

Self-splicing introns are catalytic RNAs and divided into two groups, group I intron and group II intron. They are found in mitochondria and chloroplasts genomes of plants, fungi, protists and algae, as well as in bacterial and archaebacterial (group II intron) genomes. All self-splicing introns can fold into their respective conserved secondary structures, although they are different in sequences. The typical secondary structure of a group I intron consists of approximately ten paired elements, and group Ⅱ introns have a typical structure with six double-helical domains (DI-DVI). Self-splicing introns can self-splice from their pre-RNAs by two consecutive transesterification reactions joining the flanking exons and releasing the introns. Group I introns use an exogenous G to initiate the splicing reaction, but group II introns use an internal bulged adenosine in DVI. Their respective secondary structure and protein factors are all important for the splicing reaction. Group I intron and group II intron have been used in bioengineering and also have many potential applications in functional genome and gene therapy. Self-splicing introns have become a research focus with the development of their structure and function.