RNA splicing in the T-even bacteriophage.

Area of Science:

• Molecular Biology
• RNA Splicing
• Genetics

Background:

• Group 1 introns, initially found in Tetrahymena thermophila rRNA, are present in various organisms including yeast, fungi, and chloroplasts.
• These introns can excise themselves and ligate exons in vitro, a process significantly faster in vivo.
• The identification of a group 1 intron in the T4 phage thymidylate synthase (td) gene expanded the known distribution of these elements to bacteriophages.

Purpose of the Study:

• To review the biochemical and structural properties of the T4 phage td intron.
• To compare the td intron with other newly discovered phage group 1 introns.
• To discuss the implications of these findings for understanding RNA self-splicing.

Main Methods:

• Site-directed mutagenesis was used to identify critical sequence elements in the Tetrahymena rRNA intron.
• Analysis of sequence elements involved in forming essential base-paired stem structures for self-splicing.
• Biochemical and structural characterization of the T4 phage td intron.

Main Results:

• Several sequence elements in the Tetrahymena rRNA intron are essential for forming base-paired stem structures required for self-splicing.
• These essential sequence elements are conserved in other eukaryotic group 1 introns and the T4 phage td intron.
• The T4 phage td intron shares biochemical and structural properties with other phage-derived group 1 introns.

Conclusions:

• Group 1 introns possess the capability for self-splicing, a process mediated by RNA structure rather than protein factors.
• Conserved sequence elements play a vital role in the catalytic activity of group 1 introns.
• The discovery of group 1 introns in bacteriophages provides new insights into their evolution and function.