A novel group I intron-encoded endonuclease specific for the anticodon region of tRNA(fMet) genes.

Abstract

Open reading frames (ORFs) are frequently inserted into group I self-splicing introns. These ORFs encode either maturases that are required for splicing of the intron or DNA endonucleases that promote intron mobility. A self-splicing intron in the tRNA(fMet) gene of Synechocystis PCC 6803, which has been proposed to have moved laterally within the cyanobacteria, contains an ORF that is unrelated to known intron-encoded endonucleases or maturases. Here, using an in vitro transcription-translation system, we show that this intronic ORF encodes a double-strand DNA endonuclease, I-Ssp6803I. I-Ssp6803I cleaves each strand of the intronless tRNA(fMet) gene adjacent to the anticodon triplet leaving 3 bp 3' extensions and has no activity at intron-exon boundaries. Using an in vitro cleavage assay and scanning deletion mutants of the intronless target site, the minimal recognition site was determined to be a partially palindromic 20 bp region encompassing the entire anticodon stem and loop of the tRNA(fMet) gene. I-Ssp6803I represents a novel intron-encoded DNA endonuclease and is the first example of a chromosomally encoded group I intron endonuclease in bacteria.

• Authors: R P Bonocora, D A Shub
• Journal: Molecular microbiology (Mol Microbiol) Vol. 39 Issue 5 Pg. 1299-306 (Mar 2001) ISSN: 0950-382X [Print] England
• PMID: 11251845 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Anticodon
• RNA, Transfer, Met
• Deoxyribonuclease I

Topics

• Amino Acid Sequence
• Anticodon (genetics)
• Base Sequence
• Cyanobacteria (genetics)
• Deoxyribonuclease I (genetics, metabolism)
• Introns (genetics)
• Molecular Sequence Data
• Nucleic Acid Conformation
• Open Reading Frames (genetics)
• RNA, Transfer, Met (genetics)