Spontaneous sharp bending of double-stranded DNA.

摘要: Sharply bent DNA is essential for gene regulation in prokaryotes and a major feature of eukaryotic nucleosomes viruses. The explanation normally given these phenomena that specific proteins sharply bend by application large forces, while the follows despite its intrinsic inflexibility. Here we show DNAs are 94 bp length-comparable to looped vivo-spontaneously into circles. Proteins can enhance stability such loops, but loops occur spontaneously even naked DNA. Random sequences cyclize 10(2)-10(4) times more easily than predicted from current theories bending, position up 10(5) easily. These unexpected results establish as an active participant formation regulatory complexes vivo, they point need new bending.