Cellular strategies for regulating DNA supercoiling: a single-molecule perspective.
Entangling and twisting of cellular DNA (i.e., supercoiling) are problems inherent to the helical structure of double-stranded DNA. Supercoiling affects transcription, DNA replication, and chromosomal segregation. Consequently the cell must fine-tune supercoiling to optimize these key processes. Here, we summarize how supercoiling is generated and review experimental and theoretical insights into supercoil relaxation. We distinguish between the passive dissipation of supercoils by diffusion and the active removal of supercoils by topoisomerase enzymes. We also review single-molecule studies that elucidate the timescales and mechanisms of supercoil removal.
Koster
Daniel A
DA
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
Crut
Aurélien
A
Shuman
Stewart
S
Bjornsti
Mary-Ann
MA
Dekker
Nynke H
NH
D000818:Animals; D002468:Cell Physiological Phenomena; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004278:DNA, Superhelical / Q000737:chemistry* / Q000378:metabolism; D006801:Humans
D004278:DNA, Superhelical; D004247:DNA; D004264:DNA Topoisomerases, Type I