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Nucleic Acids Res. 2011 Dec;39(22):9681-94. doi: 10.1093/nar/gkr680. Epub 2011 Aug 31.

Guiding strand passage: DNA-induced movement of the gyrase C-terminal domains defines an early step in the supercoiling cycle.

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  • 1University of Basel, Biozentrum, Biophysical Chemistry, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.

Abstract

DNA gyrase catalyzes ATP-dependent negative supercoiling of DNA in a strand passage mechanism. A double-stranded segment of DNA, the T-segment, is passed through the gap in a transiently cleaved G-segment by coordinated closing and opening of three protein interfaces in gyrase. T-segment capture is thought to be guided by the C-terminal domains of the GyrA subunit of gyrase that wrap DNA around their perimeter and cause a DNA-crossing with a positive handedness. We show here that the C-terminal domains are in a downward-facing orientation in the absence of DNA, but swing up and rotate away from the gyrase body when DNA binds. The upward movement of the C-terminal domains is an early event in the catalytic cycle of gyrase that is triggered by binding of a G-segment, and first contacts of the DNA with the C-terminal domains, and contributes to T-segment capture and subsequent strand passage.

© The Author(s) 2011. Published by Oxford University Press.

PMID:
21880594
[PubMed - indexed for MEDLINE]
PMCID:
PMC3239214
Free PMC Article
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