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Splicing of transfer RNA precursors containing intervening sequences proceeds in two distinct stages: endonucleolytic cleavage, followed by ligation. We have physically separated endonuclease and ligase activities from extracts of yeast cells, and we report properties of the partially purified endonuclease preparation. The endonuclease behaves as an(More)
We have investigated the in vitro self-splicing of a class II mitochondrial intron. A model pre-mRNA containing intron 5 gamma of the oxi 3 gene of yeast mitochondrial DNA undergoes an efficient intramolecular rearrangement reaction in vitro. This reaction proceeds under conditions distinct from those optimal for self-splicing of class I introns, such as(More)
Soluble extracts of S. cerevisiae splice tRNA precursors which contain intervening sequences. The reaction goes to completion and requires ATP for the production of mature sequence tRNA. In the absence of ATP, half-tRNA molecules accumulate. Similar half-tRNA molecules appear as kinetic intermediates and accumulate if splicing is inhibited with pure, mature(More)
Bacteriophages are the most abundant forms of life in the biosphere and carry genomes characterized by high genetic diversity and mosaic architectures. The complete sequences of 30 mycobacteriophage genomes show them collectively to encode 101 tRNAs, three tmRNAs, and 3,357 proteins belonging to 1,536 "phamilies" of related sequences, and a statistical(More)
Mycobacteriophages are viruses that infect mycobacterial hosts such as Mycobacterium smegmatis and Mycobacterium tuberculosis. All mycobacteriophages characterized to date are dsDNA tailed phages, and have either siphoviral or myoviral morphotypes. However, their genetic diversity is considerable, and although sixty-two genomes have been sequenced and(More)
The intermediates of the yeast tRNA splicing reaction have been characterized. The intervening sequence is excised as an unique linear molecule. It has 5'-hydroxyl and 3'-phosphate termini. Correspondingly, the half-tRNA molecules are shown to have a 3'-phosphate terminus on the 5' half and 5'-hydroxyl terminus on the 3' half. These isolated halves have(More)
UNLABELLED Genomic analysis of a large set of phages infecting the common host Mycobacterium smegmatis mc(2)155 shows that they span considerable genetic diversity. There are more than 20 distinct types that lack nucleotide similarity with each other, and there is considerable diversity within most of the groups. Three newly isolated temperate(More)
The conjugative element pRS01 from Lactococcus lactis encodes the putative relaxase protein LtrB. The ltrB gene is interrupted by the functional group II intron Ll.ltrB. Accurate splicing of the two ltrB exons is required for synthesis of the mRNA encoding the LtrB conjugative relaxase and subsequent plasmid transfer. A conjugation-based genetic assay was(More)
The 5' splice junction (5'SJ) of Group II intron transcripts is subject to a specific hydrolysis reaction (SJH). This reaction occurs either within a single transcript containing intron sequences through domain 5 (D5) or by cooperation of two separate transcripts, one bearing the 5'SJ and another contributing D5 (1). In this report we describe the latter(More)