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1zi0
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(New page: 200px<br /><applet load="1zi0" size="450" color="white" frame="true" align="right" spinBox="true" caption="1zi0, resolution 2.60Å" /> '''A Superhelical Spira...)
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Revision as of 05:20, 21 November 2007
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A Superhelical Spiral in Escherichia coli DNA Gyrase A C-terminal Domain Imparts Unidirectional Supercoiling Bias
Overview
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.
About this Structure
1ZI0 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
A superhelical spiral in the Escherichia coli DNA gyrase A C-terminal domain imparts unidirectional supercoiling bias., Ruthenburg AJ, Graybosch DM, Huetsch JC, Verdine GL, J Biol Chem. 2005 Jul 15;280(28):26177-84. Epub 2005 May 15. PMID:15897198
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