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Structure and operation of the DNA-translocating type I DNA restriction enzymes.

TitleStructure and operation of the DNA-translocating type I DNA restriction enzymes.
Publication TypeJournal Article
Year of Publication2012
AuthorsKennaway CK, Taylor JE, Song CFeng, Potrzebowski W, Nicholson W, White JH, Swiderska A, Obarska-Kosinska A, Callow P, Cooper LP, Roberts GA, Artero J-B, Bujnicki JM, Trinick J, G Kneale G, Dryden DTF
JournalGenes Dev
Date Published2012 Jan 1
KeywordsDeoxyribonucleases, Type I Site-Specific, DNA Restriction Enzymes, Microscopy, Electron, Models, Molecular, Negative Staining, Protein Structure, Tertiary

Type I DNA restriction/modification (RM) enzymes are molecular machines found in the majority of bacterial species. Their early discovery paved the way for the development of genetic engineering. They control (restrict) the influx of foreign DNA via horizontal gene transfer into the bacterium while maintaining sequence-specific methylation (modification) of host DNA. The endonuclease reaction of these enzymes on unmethylated DNA is preceded by bidirectional translocation of thousands of base pairs of DNA toward the enzyme. We present the structures of two type I RM enzymes, EcoKI and EcoR124I, derived using electron microscopy (EM), small-angle scattering (neutron and X-ray), and detailed molecular modeling. DNA binding triggers a large contraction of the open form of the enzyme to a compact form. The path followed by DNA through the complexes is revealed by using a DNA mimic anti-restriction protein. The structures reveal an evolutionary link between type I RM enzymes and type II RM enzymes.

Alternate JournalGenes Dev.
PubMed ID22215814
PubMed Central IDPMC3258970
Grant List080304/Z/06/Z / / Wellcome Trust / United Kingdom
BB/D001870/1 / / Biotechnology and Biological Sciences Research Council / United Kingdom
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