Enzymatic Reactions on Topologically-Interlocked DNA StructuresInside a DNA Origami Frame

摘要

Topoisomerases (Topos) are essential enzymes that are required for the management ofDNA superhelicity,and chromosome condensation and segregation.Also,these enzymesplay an important role in various biological processes such as replication,transcription andrecombination.1 These enzymes were also identified as the targets of a variety oftherapeutics including anticancer drugs.Since then the structural and mechanistic studies ofthese enzymes have gained significant attention.2 Topos resolve the topological constraintsby transiently cleaving the phosphodiester bond,which generates a Topo-DNA cleavagecomplex.Once the winding stress is resolved,the Topo-mediated DNA break is resealed.This process is critical for the healthy cells to survive and function normally.Failure toreseal the DNA break can ultimately lead to cell death.Despite the development of variousTopo-inhibitors,the mechanism of action of these anticancer drug molecules is not wellknown.Thus,to understand the Topos reaction and the mechanism of the inhibitors,it isnecessary to develop methods to characterize each reaction step of Topo.