1ab4
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(New page: 200px<br /><applet load="1ab4" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ab4, resolution 2.8Å" /> '''59KDA FRAGMENT OF GYR...)
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Revision as of 08:36, 20 November 2007
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59KDA FRAGMENT OF GYRASE A FROM E. COLI
Overview
DNA gyrase is a type II DNA topoisomerase from bacteria that introduces, supercoils into DNA. It catalyses the breakage of a DNA duplex (the G, segment), the passage of another segment (the T segment) through the, break, and then the reunification of the break. This activity involves the, opening and dosing of a series of molecular 'gates' which is coupled to, ATP hydrolysis. Here we present the crystal structure of the, 'breakage-reunion' domain of the gyrase at 2.8 A resolution. Comparison of, the structure of this 59K (relative molecular mass, 59,000) domain with, that of a 92K fragment of yeast topoisomerase II reveals a very different, quaternary organization, and we propose that the two structures represent, two principal conformations that participate in the enzymatic pathway. The, gyrase structure reveals a new dimer contact with a grooved concave, surface for binding the G segment and a cluster of conserved charged, residues surrounding the active-site tyrosines. It also shows how breakage, of the G segment can occur and, together with the topoisomerase II, structure, suggests a pathway by which the T segment can be released, through the second gate of the enzyme. Mutations that confer resistance to, the quinolone antibacterial agents cluster at the new dimer interface, indicating how these drugs might interact with the gyrase-DNA complex.
About this Structure
1AB4 is a Single protein structure of sequence from Escherichia coli. Active as DNA topoisomerase (ATP-hydrolyzing), with EC number 5.99.1.3 Full crystallographic information is available from OCA.
Reference
Crystal structure of the breakage-reunion domain of DNA gyrase., Morais Cabral JH, Jackson AP, Smith CV, Shikotra N, Maxwell A, Liddington RC, Nature. 1997 Aug 28;388(6645):903-6. PMID:9278055
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