Group II introns are categorized as self-catalytic ribozymes that can perform self-splicing. This splicing can be used to further study the roles that proteins have in facilitating RNA-catalyzed reactions. Genetic screening of the maize genome has revealed two nuclear genes needed to facilitate group II intron splicing in the chloroplast; crs1 and crs2. The research focused on crs1 because researchers believed that this gene facilitates atpF intron splicing. Several reasons have led them to this belief. First, CRS1 has been observed in ribonucleorprotein complexes in the chloroplast with the atpF intron. Second, CRS1 is basic and has a repeated domain with features that suggest a RNA-binding domain. And lastly, the mutated crs1 gene resulted in disrupted splicing of the atpF intron. These findings are used to support the idea that CRS1 is used to influence splicing of the atpF intron by directly binding to it. Also, analysis of the crs1 mutant provides evidence that CRS1 is involved in more than just atpF splicing but also in chloroplast translation.
Reference:
Till B., Schmitz-Linneweber C., Williams-Carrier R., Barkan A. 2001. “CRS1 is a Novel Group II Intron Splicing Factor that was Derived from a Domain of Ancient Origin”. RNA: A Publication of the RNA Society. September 2001. 7: 1227-1238
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