| The junction-resolving enzyme T7 endonuclease I: quaternary structure and interaction with DNA. | |
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MedLine Citation:
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PMID: 9236119 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Endonuclease I is a DNA junction-selective resolving enzyme from bacteriophage T7. Using a nuclease-defective mutant that retains normal binding to DNA we show that the protein binds to four-way DNA junctions as a dimer, in common with other junction-resolving enzymes studied. Gel filtration and chemical crosslinking indicate that endonuclease I also exists in free solution as a dimer together with a tetramer and higher molecular mass aggregates. However, in marked contrast with other junction-resolving enzymes, there is no detectable subunit exchange under normal conditions. Only by exposure to 6 M urea could we induce subunit exchange, and this was used to generate heterodimeric species containing one active and one inactive subunit. Using a supercoil-stabilised cruciform substrate we demonstrate that an active subunit of endonuclease I can act as a junction-specific nuclease in a heterodimeric combination with an inactive subunit. However, the two subunits of a fully active homodimeric enzyme each cleave the phosphodiester backbone of a cruciform within the lifetime of the DNA-protein complex. |
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Authors:
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M J Parkinson; D M Lilley |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of molecular biology Volume: 270 ISSN: 0022-2836 ISO Abbreviation: J. Mol. Biol. Publication Date: 1997 Jul |
Date Detail:
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Created Date: 1997-08-15 Completed Date: 1997-08-15 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 2985088R Medline TA: J Mol Biol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 169-78 Citation Subset: IM |
Affiliation:
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Department of Biochemistry, The University of Dundee, UK. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Bacteriophage T7
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enzymology*,
genetics DNA, Viral / metabolism* DNA-Binding Proteins / metabolism Deoxyribonuclease I / chemistry*, genetics, metabolism Dimerization Protein Conformation* Protein Denaturation Solutions Urea / metabolism |
| Chemical | |
Reg. No./Substance:
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0/DNA, Viral; 0/DNA-Binding Proteins; 0/Solutions; 57-13-6/Urea; EC 3.1.21.1/Deoxyribonuclease I |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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