Restriction endonuclease Sst 12I from a strain of Streptomyces sp. recognizing the nucleotide sequence 5'-CTGCAG-3'

A new restriction endonuclease Sst12I belonging to the II type and recognizing the sequence 5'-CTGCAG-3' was isolated from the bacterial strain Streptomyces sp. St-12. The enzyme hydrolyzes DNA between adenine and guanine residues; thus, it is a true isoschizomer of restrictase PstI. In contrast to PstI, the restriction endonuclease Sst12I hydrolyses DNA both at 37 degrees and 55 degrees C and remains active after long-term storage.     

PsiI, a novel restriction endonuclease recognizing the DNA sequence 5'-TTA downward arrow TAA-3'

PsiI, a novel restriction endonuclease produced by the bacterial strain Pseudomonas sp. SE-G49, has been isolated and characterized. The enzyme cleaves DNA in the middle of its palindromic recognition sequence 5'-TTA downward arrow TAA-3'. Thus, PsiI belongs to a rare group of type II restriction endonucleases whose recognition sites consist of AT base pairs only.     

A new restriction endonuclease Eco31I recognizing a non-palindromic sequence

A restriction endonuclease with a novel site-specificity has been isolated from the Escherichia coli strain RFL31. The nucleotide sequences around a single Eco31I cut on pBR322 DNA and two cuts of lambda DNA have been compared. A common 5'GAGACC 3'CTCTGG sequence occurs near each cleavage site. Precise mapping of the cleavages in both DNA strands places the cuts five nucleotides to the left of the upper sequence and one nucleotide to the left of the lower sequence. This enabled us to deduce the following recognition and cleavage specificity of Eco31I: 5' GGTCTCN decreases 3' CCAGAGN NNNN increases.     

MamI, a novel class-II restriction endonuclease from Microbacterium ammoniaphilum recognizing 5'-GATNN decreases NNATC-3'

A new site-specific class-II restriction endonuclease, MamI, has been discovered in the nonsporulating Gram+ Microbacterium ammoniaphilum. MamI recognition sequence and cleavage positions were deduced using experimental and computer-assisted mapping and sequencing approaches. MamI cleavage specificity corresponds to: [formula: see text] The novel 43-kD enzyme recognizes a palindromic hexanucleotide interrupted by four ambiguous nucleotides. MamI cleavage positions are located in the center of the recognition sequence resulting in blunt-ended fragments after cleavage in the presence of Mg2+ ions. MamI is inhibited by N6-methyladenine residues. In case of overlapping sequences of MamI and Escherichia coli-coded DNA modification methyltransferase M.EcodamI (5'-[formula: see text]-3'), cleavage of DNA isolated from E. coli wild-type cells will be inhibited. By applying incubation conditions forcing star activity, relaxing of MamI sequence specificity is observed (MamI*).     

McrI: a novel class-II restriction endonuclease from Micrococcus cryophilus recognizing 5'-CGRY/CG-3'

A new class-II restriction endonuclease, McrI, with a novel sequence specificity as isolated from the Gram-positive eubacterium Micrococcus cryophilus. McrI recognizes the palindromic hexanucleotide sequence. [sequence: see text] The novel enzyme in the presence of Mg2(+)-ions cleaves specifically both strands as indicated by the arrows. The staggered cuts generate 3'-protruding ends with single-stranded 5'-RY-3' dinucleotide extensions. The McrI recognition sequence was deduced from mapping data on DNAs of bacteriophages theta X174RF and M13mp18RF characterized by one and four cleavage sites, respectively. The cut positions within both strands of the recognition sequence were determined in sequencing experiments by analyzing hydrolysis of phosphodiester bonds within a polylinker region of M13mp18RF DNA containing an additional McrI recognition site including treatment with T4 DNA polymerase. The novel enzyme may be a useful tool for cloning experiments by completion of the enzymes EclXI (5'-C/GGCCG-3'), NotI (5'-GC/GGCCGC-3'), PvuI (5'-CGAT/CG-3') as well as EaeI (5'-Y/GGCCR-3') and XhoII (5'-Y/GATCR-3') characterized by partly identical sequence specificities.     

A new restriction endonuclease Eco31I recognizing a non-palindromic sequence

A restriction endonuclease with a novel site-specificity has been isolated from the Escherichia coli strain RFL31. The nucleotide sequences around a single Eco31I cut on pBR322 DNA and two cuts of λ DNA have been compared. A common ^5′GAGACC_3′CTCTGG sequence occurs near each cleavage site. Precise mapping of the cleavages in both DNA strands places the cuts five nucleotides to the left of the upper sequence and one nucleotide to the left of the lower sequence. This enabled us to deduce the following recognition and cleavage specificity of Eco31I: 5 ′ G G T C T C N ↓ 3 ′ C C A G A G N N N N N ↑     

OliI, a unique restriction endonuclease that recognizes the discontinuous sequence 5'-CACNN NGTG-3'

A new type II restriction endonuclease designated OLI:I has been partially purified from the halophilic bacterium Oceanospirillum linum 4-5D. OLI:I recognizes the interrupted hexanucleotide palindrome 5'-CACNN NNGTG-3' and cleaves it in the center generating blunt-ended DNA fragments.     

5' nucleotide sequence of sindbis viral RNA.

The 5' sequence of Sindbis viral RNA is m (7)G(5') pppApUpGp...     

Novel specific endonuclease activity recognizing a 10-bp sequence

We report here the generation of a novel restriction endonuclease (ENase) activity with the 10-bp recognition sequence,

This specificity could be achieved by first methylating a substrate DNA with M·MamI in vivo, followed by in vitro R·DpnI restriction.     

Restriction endonuclease BsoFI is sensitive to the 5'-methylation of deoxycytidines in its recognition sequence.

The isoschizomeric restriction endonucleases Fnu4HI and BsoFI cleave DNA at 5'-GCdecreasesNGC-3' sequences. Fnu4HI has been shown to be inhibited by 5'-CG-3'methylation in the sequences 5'-GmCGGC-3' or 5'-GCGGmCG-3'. We have now investigated the methylation sensitivity of BsoFI by testing its activity on plasmid DNA 5'-CG-3' methylated with the M.SssI DNA methyltransferase or on synthetic (CGG)n repetitive oligodeoxyribonucleotides which have been partly or completely C methylated. The data demonstrate that BsoFI cannot cleave at its recognition sequence when it is completely 5'-CG-3' methylated. These enzymes have proven to be useful in analyses of the methylation status in (CGG)n repeats of the human genome.     

PfoI,a unique type II restriction endonuclease that recognises the sequence 5'-T downward arrow CCNGGA-3'

A new type II restriction endonuclease designated PfoI has been partially purified from Pseudomonas fluorescens biovar 126. PfoI recognises the interrupted hexanucleotide palindromic sequence 5'-T downward arrow CCNGGA-3' and cleaves DNA to produce protruding pentanucleotide 5'-ends.