Unexpected structural diversity in DNA recombination: the restriction endonuclease connection.
Transposition requires a coordinated series of DNA breakage and joining reactions. The Tn7 transposase contains two proteins: TnsA, which carries out DNA breakage at the 5' ends of the transposon, and TnsB, which carries out breakage and joining at the 3' ends of the transposon. TnsB is a member of the retroviral integrase superfamily whose hallmark is a conserved DDE motif. We report here the structure of TnsA at 2.4 A resolution. Surprisingly, the TnsA fold is that of a type II restriction endonuclease. Thus, Tn7 transposition involves a collaboration between polypeptides, one containing a DDE motif and one that does not. This result indicates that the range of biological processes that utilize restriction enzyme-like folds also includes DNA transposition.
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. ahickman@helix.nih.gov
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Hickman
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Li
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Mathew
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May
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Craig
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Dyda
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry*; D029968:Escherichia coli Proteins; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011995:Recombination, Genetic; D013329:Structure-Activity Relationship; D019895:Transposases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C098908:TnsA protein, E coli; D004247:DNA; D019895:Transposases; D015252:Deoxyribonucleases, Type II Site-Specific; D008274:Magnesium