AI Article Synopsis
- The study used magnetic tweezers and atomic force microscopy to investigate how the cationic surfactant C12 C6 C12 Br2 causes DNA to condense in a stepwise manner, with each event reducing DNA length by around 100 nm at forces between 0.5 and 4 pN.
- Higher stretching forces (above 6 pN) can reverse this process, releasing approximately 60 nm of DNA in a similar stepwise fashion.
- The findings suggest a new model of DNA condensation involving the formation of independent beadlike structures that pack into denser configurations, resembling behavior observed in chromatin assembly.
Article Abstract
Using a magnetic tweezers (MT) apparatus and an atomic force microscope (AFM), we studied the condensation of DNA induced by the cationic gemini surfactant hexyl-alpha,omega-bisdodecyldimethylammonium bromide (C12 C6 C12 Br2). Stepwise condensation events were found for forces from 0.5 to 4 pN, with a decrease in DNA extension by approximately 100 nm in each condensation event. Applied stretching forces larger than 6 pN were found to be able to decondense the condensates in a similar intermittent stepwise manner, but with approximately 60 nm of DNA released in each decondensation event. These observations are consistent with AFM images that show beadlike structures on DNA. The results lead to a model in which, during condensation, independent beadlike structures are initially formed on DNA, and as the local density of the beads increases, they compact into higher-order structures while maintaining their independence. The condensation process is different from any previously reported condensation process, but it is somewhat similar to that of chromatin assembly.
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| http://dx.doi.org/10.1021/jp8078887 | DOI Listing |
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