The 1016-base-pair (bp) intron in the T4 bacteriophage thymidylate synthase gene (td) contains a 735-bp open reading frame that encodes a protein product with endonucleolytic activity. The endonuclease shows specificity for the intronless form of the td gene. Highly purified endonuclease cleaves the DNA of the intronless form of the td gene in vitro at 24 bp upstream of the exon 1-exon 2 juncti...

Bal31 deletion experiments on clones of the PaeR7 restriction-modification system from Pseudomonas aeruginosa demonstrate that it is arranged as an operon, with the methylase gene preceding the endonuclease gene. The DNA sequence of this operon agrees with in vitro transcription-translation assays which predict proteins of 532 amino acids, Mr = 59,260 daltons, and 246 amino acids, Mr = 27,280 d...

A mobile group I intron containing two ribozyme domains and a homing endonuclease gene (twin-ribozyme intron organization) can integrate by reverse splicing into the small subunit rRNA of bacteria and yeast. The integration is sequence-specific and corresponds to the natural insertion site (homing site) of the intron. The reverse splicing is independent of the homing endonuclease gene, but is d...

To study the factors essential for a functional restriction system, the PaeR7 restriction-modification system has been introduced and expressed in murine cells. Transfer of this system was accomplished in two steps. First, cells containing sufficient PaeR7 methylase to completely methylate the mouse genome were constructed. In the second step, the mouse metallothionein promoter-regulated, endon...

Endonuclease VII is a Holliday-structure resolving enzyme of phage T4 which cleaves at junctions of branched DNAs and at mispairings. In extension of these findings we report the following: i) Endonuclease VII can discriminate between a large heteroduplex loop and a TT mismatch arranged in tandem, 6 nt distant from each other, in the same heteroduplex molecule. The enzyme cleaves two nucleotide...

A second DNA site-specific (restriction) endonuclease (R.CviAII) and its cognate adenine DNA methyltransferase (M.CviAII) were isolated from virus PBCV-1 infected Chlorella strain NC64A cells. R.CviAII, a heteroschizomer of the bacterial restriction endonuclease NlaIII, recognizes the sequence CATG, and does not cleave CmATG sequences. However, unlike NlaIII, which cleaves after the G and does ...

The type II restriction endonuclease, Bam HI, has been overexpressed in E. coli by cloning the Bam HI gene in frame with an E. coli Ribosome Binding Site (RBS) under the T7 promoter of an E. coli expression vector pRSET A. The expression level of Bam HI endonuclease using this construct was found to be higher than that reported of the overexpressing clone pAEK14. Our overexpressing clone, pAABR...

UV damage endonuclease (Uve1p) from Schizosaccharomyces pombe was initially described as a DNA repair enzyme specific for the repair of UV light-induced photoproducts and proposed as the initial step in an alternative excision repair pathway. Here we present biochemical and genetic evidence demonstrating that Uve1p is also a mismatch repair endonuclease which recognizes and cleaves DNA 5' to th...