We have used atomic force microscopy to examine the conformations of a DNA plasmid which contains a repeated sequence that is able to form an unusual DNA structure. About 16.8% of plasmid molecules containing the sequence (T15A15)2 adopted a compacted rod-shaped form compared to 89.5% of control molecules without the repeated sequence. The secondary structure- forming sequence therefore changed the conformation of the supercoiled plasmid in the predicted manner. In about 40.2% of plasmids with the (T15A15)2 sequence a short, branched structure was visible. We speculate that this object may represent a non-standard local DNA conformation, and suggest an interpretation of the structure.
|Number of pages||9|
|Publication status||Published - 19 Oct 1999|
- Atomic force microscopy
- DNA structure
- Supercoiling Repeated sequences