Limanskii A.

Oversupercoiling and compactization of supercoiled DNA

TSitologiia i genetika 2005, v 39, Issue 2, 64-71

Supercoiled DNA pGEMEX with length of 3993 nucleotides was immobilized on the different substrates (freshly cleaved mica, standard aminomica and modified aminomica) and visualized by atomic force microscopy. Plectonomically supercoiled DNA molecules as well as molecules with extremely high level of compactization (i.e. molecules with considerably higher supercoiled density values in comparing with experimentally measured and theoretically investigated ones) were visualized on modified aminomica. At the further increasing of the compactization level an axis length of oversupercoiled molecules was decreased from ~390 nm to ~ 140 nm and formation of minitoroids of ~ 50 nm diameter and molecules in sphere conformation were observed. Model of possible conformational transitions of supercoiled DNA was proposed basing on the analysis of captured AFM images at the increasing of supercoiling density.

Limanskii A. Oversupercoiling and compactization of supercoiled DNA // Tsitol Genet. – 2005. – 39(2). – P. 64-71.