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| [[Image:1zi0.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1zi0| PDB=1zi0 | SCENE= }} | | {{STRUCTURE_1zi0| PDB=1zi0 | SCENE= }} |
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| '''A Superhelical Spiral in Escherichia coli DNA Gyrase A C-terminal Domain Imparts Unidirectional Supercoiling Bias'''
| | ===A Superhelical Spiral in Escherichia coli DNA Gyrase A C-terminal Domain Imparts Unidirectional Supercoiling Bias=== |
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| ==Overview==
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| DNA gyrase is unique among type II topoisomerases in that its DNA supercoiling activity is unidirectional. The C-terminal domain of the gyrase A subunit (GyrA-CTD) is required for this supercoiling bias. We report here the x-ray structure of the Escherichia coli GyrA-CTD (Protein Data Bank code 1ZI0). The E. coli GyrA-CTD adopts a circular-shaped beta-pinwheel fold first seen in the Borrelia burgdorferi GyrA-CTD. However, whereas the B. burgdorferi GyrA-CTD is flat, the E. coli GyrA-CTD is spiral. DNA relaxation assays reveal that the E. coli GyrA-CTD wraps DNA inducing substantial (+) superhelicity, while the B. burgdorferi GyrA-CTD introduces a more modest (+) superhelicity. The observation of a superhelical spiral in the present structure and that of the Bacillus stearothermophilus ParC-CTD structure suggests unexpected similarities in substrate selectivity between gyrase and Topo IV enzymes. We propose a model wherein the right-handed ((+) solenoidal) wrapping of DNA around the E. coli GyrA-CTD enforces unidirectional (-) DNA supercoiling.
| | The line below this paragraph, {{ABSTRACT_PUBMED_15897198}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 15897198 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_15897198}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Spiralling beta pinwheel]] | | [[Category: Spiralling beta pinwheel]] |
| [[Category: Topoisomerase]] | | [[Category: Topoisomerase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 17:38:59 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 17:38:28 2008'' |
