In the current era of massive discoveries of noncoding RNAs within genomes, being able to infer a function from a nucleotide sequence is of paramount interest. Although studies of individual group I introns have identified self-splicing and nonself-splicing examples, there is no overall understanding of the prevalence of self-splicing or the factors that determine it among the >2300 group I introns sequenced to date. Here, the self-splicing activities of 12 group I introns from various organisms were assayed under six reaction conditions that had been shown previously to promote RNA catalysis for different RNAs. Besides revealing that assessing self-splicing under only one condition can be misleading, this survey emphasizes that in vitro self-splicing efficiency is correlated with the GC content of the intron (>35% GC was generally conductive to self-splicing), and with the ability of the introns to form particular tertiary interactions. Addition of the Neurospora crassa CYT-18 protein activated splicing of two nonself-splicing introns, but inhibited the second step of self-splicing for two others. Together, correlations between sequence, predicted structure and splicing begin to establish rules that should facilitate our ability to predict the self-splicing activity of any group I intron from its sequence.
Vicens, Quentin; Paukstelis, Paul J.; Westhof, Eric; Lambowitz, Alan M.; and Cech, Thomas R., "Toward Predicting Self-Splicing and Protein-Facilitated Splicing of Group I Introns" (2008). Chemistry & Biochemistry Faculty Contributions (1986-2018). 17.