DNA-protein interaction, DNA supercoiling, chloroquine, protein p53

The tumor suppressor protein p53 belongs to the checkpoint proteins. Its function is closely related to maintaining genetic integrity of the cells and to defence against malignant transformation. Biological activity of p53 is dependent on its ability to interact with DNA. It was found that p53 bound to DNA sequence .specifically or sequence-non-specifically to both positively or negatively supercoiled DNA. This work was focused on study of supercoil-selective p53 DNA interactions using immuprecipitation at magnetic beads. We tested influence of intercalative drug chloroquine (CQ) on p53 binding. We found, that in absence of CQ p53 bound scDNA with higher preference then linDNA, but in presence of higher concentration of CQ, DNA relaxed and p53 bound to relaxed and linDNA with the same affinity. Due to further increasing of CQ concentration, DNA became positively supercoiled and the preference for this DNA was remarkably higher again.