Biomaterial Database

Type III restriction-modification enzymes: a historical perspective. 2014

Desirazu N Rao, and David T F Dryden, and Shivakumara Bheemanaik

Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India and School of Chemistry, The King's Buildings, The University of Edinburgh, Edinburgh EH9 3JJ, Scotland, UK.

Restriction endonucleases interact with DNA at specific sites leading to cleavage of DNA. Bacterial DNA is protected from restriction endonuclease cleavage by modifying the DNA using a DNA methyltransferase. Based on their molecular structure, sequence recognition, cleavage position and cofactor requirements, restriction-modification (R-M) systems are classified into four groups. Type III R-M enzymes need to interact with two separate unmethylated DNA sequences in inversely repeated head-to-head orientations for efficient cleavage to occur at a defined location (25-27 bp downstream of one of the recognition sites). Like the Type I R-M enzymes, Type III R-M enzymes possess a sequence-specific ATPase activity for DNA cleavage. ATP hydrolysis is required for the long-distance communication between the sites before cleavage. Different models, based on 1D diffusion and/or 3D-DNA looping, exist to explain how the long-distance interaction between the two recognition sites takes place. Type III R-M systems are found in most sequenced bacteria. Genome sequencing of many pathogenic bacteria also shows the presence of a number of phase-variable Type III R-M systems, which play a role in virulence. A growing number of these enzymes are being subjected to biochemical and genetic studies, which, when combined with ongoing structural analyses, promise to provide details for mechanisms of DNA recognition and catalysis.

UI	MeSH Term	Description	Entries
D003090	Coliphages	Viruses whose host is Escherichia coli.	Escherichia coli Phages,Coliphage,Escherichia coli Phage,Phage, Escherichia coli,Phages, Escherichia coli
D015254	DNA Modification Methylases	Enzymes that are part of the restriction-modification systems. They are responsible for producing a species-characteristic methylation pattern, on either adenine or cytosine residues, in a specific short base sequence in the host cell's own DNA. This methylated sequence will occur many times in the host-cell DNA and remain intact for the lifetime of the cell. Any DNA from another species which gains entry into a living cell and lacks the characteristic methylation pattern will be recognized by the restriction endonucleases of similar specificity and destroyed by cleavage. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms.	DNA Modification Methyltransferases,Modification Methylases,Methylases, DNA Modification,Methylases, Modification,Methyltransferases, DNA Modification,Modification Methylases, DNA,Modification Methyltransferases, DNA
D015263	Deoxyribonucleases, Type III Site-Specific	Enzyme systems composed of two subunits and requiring ATP and magnesium for endonucleolytic activity; they do not function as ATPases. They exist as complexes with modification methylases of similar specificity listed under EC 2.1.1.72 or EC 2.1.1.73. The systems recognize specific short DNA sequences and cleave a short distance, about 24 to 27 bases, away from the recognition sequence to give specific double-stranded fragments with terminal 5'-phosphates. Enzymes from different microorganisms with the same specificity are called isoschizomers. EC 3.1.21.5.	DNA Restriction Enzymes, Type III,DNase, Site-Specific, Type III,Restriction Endonucleases, Type III,Type III Restriction Enzymes,DNase, Site Specific, Type III,Deoxyribonucleases, Type III, Site Specific,Deoxyribonucleases, Type III, Site-Specific,Site-Specific DNase, Type III,Type III Site Specific DNase,Type III Site Specific Deoxyribonucleases,Type III Site-Specific DNase,Type III Site-Specific Deoxyribonucleases,Deoxyribonucleases, Type III Site Specific,Site Specific DNase, Type III
D049673	History, 20th Century	Time period from 1901 through 2000 of the common era.	20th Century History,20th Cent. History (Medicine),20th Cent. History of Medicine,20th Cent. Medicine,Historical Events, 20th Century,History of Medicine, 20th Cent.,History, Twentieth Century,Medical History, 20th Cent.,Medicine, 20th Cent.,20th Cent. Histories (Medicine),20th Century Histories,Cent. Histories, 20th (Medicine),Cent. History, 20th (Medicine),Century Histories, 20th,Century Histories, Twentieth,Century History, 20th,Century History, Twentieth,Histories, 20th Cent. (Medicine),Histories, 20th Century,Histories, Twentieth Century,History, 20th Cent. (Medicine),Twentieth Century Histories,Twentieth Century History
D049674	History, 21st Century	Time period from 2001 through 2100 of the common era.	21st Century History,21st Cent. History (Medicine),21st Cent. History of Medicine,21st Cent. Medicine,Historical Events, 21st Century,History of Medicine, 21st Cent.,History, Twenty-first Century,Medical History, 21st Cent.,Medicine, 21st Cent.,21st Cent. Histories (Medicine),21st Cent. Medicines,21st Century Histories,Cent. Histories, 21st (Medicine),Cent. History, 21st (Medicine),Cent. Medicine, 21st,Cent. Medicines, 21st,Century Histories, 21st,Century Histories, Twenty-first,Century History, 21st,Century History, Twenty-first,Histories, 21st Cent. (Medicine),Histories, 21st Century,Histories, Twenty-first Century,History, 21st Cent. (Medicine),History, Twenty first Century,Medicines, 21st Cent.,Twenty-first Century Histories,Twenty-first Century History
D053837	DNA Cleavage	A reaction that severs one of the covalent sugar-phosphate linkages between NUCLEOTIDES that compose the sugar phosphate backbone of DNA. It is catalyzed enzymatically, chemically or by radiation. Cleavage may be exonucleolytic - removing the end nucleotide, or endonucleolytic - splitting the strand in two.