Direct measurement of DNA bending by type IIA topoisomerases: implications for non-equilibrium topology simplification.

ABSTRACT: Type IIA topoisomerases modify DNA topology by passing one segment of duplex DNA (transfer or T-segment) through a transient double-strand break in a second segment of DNA (gate or G-segment) in an ATP-dependent reaction. Type IIA topoisomerases decatenate, unknot and relax supercoiled DNA to levels below equilibrium, resulting in global topology simplification. The mechanism underlying this non-equilibrium topology simplification remains speculative. The bend angle model postulates that non-equilibrium topology simplification scales with the bend angle imposed on the G-segment DNA by the binding of a type IIA topoisomerase. To test this bend angle model, we used atomic force microscopy and single-molecule Förster resonance energy transfer to measure the extent of bending imposed on DNA by

SUBMITTER: Hardin AH 

PROVIDER: S-EPMC3141238 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature