title: Toward predicting self-splicing and protein-facilitated splicing of group I introns.
abstract: 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.
authors.affiliation: Howard Hughes Medical Institute, University of Colorado, Department of Chemistry and Biochemistry, Boulder, Colorado 80309-0215, USA. quentin.vicens@colorado.edu
authors.forename: Quentin
authors.initials: Q
authors.lastname: Vicens
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Paukstelis
authors.forename: Eric
authors.initials: E
authors.lastname: Westhof
authors.forename: Alan M
authors.initials: AM
authors.lastname: Lambowitz
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Cech