Group II introns are found in bacteria and cell organelles (plastids, mitochondria) and are thought to represent the evolutionary ancestors of spliceosomal introns. It is generally believed that group II introns are selfish genetic elements that do not have any function. Here, we have scrutinized this assumption by analyzing two group II introns that interrupt a plastid gene (ycf3) involved in ...

Group II introns are self-splicing RNAs found in eubacteria, archaea, and eukaryotic organelles. They are mechanistically similar to the metazoan nuclear spliceosomal introns; therefore, group II introns have been invoked as the progenitors of the eukaryotic pre-mRNA introns. However, the ability of group II introns to function outside of the bacteria-derived organelles is debatable, since they...

BACKGROUND The group I intron, a ribozyme that catalyzes its own splicing reactions in the absence of proteins in vitro, is a potential target for rational engineering and attracted our interest due to its potential utility in gene repair using trans-splicing. However, the ribozyme activity of a group I intron appears to be facilitated by RNA chaperones in vivo; therefore, the efficiency of sel...

BACKGROUND Based on previous studies, it was suspected that the mitochondrial rns gene within the Ophiostomatales is rich in introns. This study focused on a collection of strains representing Ophiostoma piliferum, Ophiostoma pluriannulatum and related species that cause blue-stain; these fungi colonize the sapwood of trees and impart a dark stain. This reduces the value of the lumber. The goal...

Twenty-two years after their discovery as ribozymes, the self-splicing group I introns are finally disclosing their architecture at the atomic level. The crystal structures of three group I introns solved at moderately high resolution (3.1-3.8A) reveal a remarkably conserved catalytic core bound to the metal ions required for activity. The structure of the core is stabilized by an intron-specif...

Group I introns constitute excellent systems for analyzing the relationship between RNA tertiary folding and catalysis. Within a hierarchical framework interpretation of RNA folding, secondary structure motifs subtend RNA three-dimensional (3D) architecture. Thus, mutations in two-dimensional motifs are expected to have effects different from those disrupting 3D contacts. Using UV spectroscopy,...

Background: Group I introns are valuable for studying RNA folding and chaperone proteins. Results: A catalytic activity assay was developed and used to demonstrate two prominent phases for Azoarcus ribozyme folding. The slow phase displays hallmarks of a misfolded intermediate. Conclusion: This RNA accumulates a misfolded intermediate and interacts productively with RNA chaperones. Significance...

The origin and modes of transmission of introns remain matters of much debate. Previous studies of the group I intron in the angiosperm cox1 gene inferred frequent angiosperm-to-angiosperm horizontal transmission of the intron from apparent incongruence between intron phylogenies and angiosperm phylogenies, patchy distribution of the intron among angiosperms, and differences between cox1 exonic...

Mitochondrial genomes in the true fungi are highly variable both in size and organization. Most of this size variation is due to the presence of introns and intron-encoded open reading frames (ORFs). The objectives for this work were to examine the mitochondrial small-subunit ribosomal RNA (rns) gene of strains of Ophiostoma minus for the presence of introns and to characterize such introns and...