ABSTRACT
We demonstrate that DNA-loops can stochastically propel the site-specifically bound transcription factors (TFs) towards the promoters. The gradual release of elastic energy stored on the DNA-loops is the source of propulsion. The speed of looping mediated interaction of TFs with promoters is several times faster than the sliding mode. Elastic and entropic energy barriers associated with the looping actually shape up the distribution of distances between TF binding sites and promoters. The commonly observed multiprotein binding in gene regulation is acquired through evolution to overcome the looping energy barrier. Presence of nucleosomes on the genomic DNA of eukaryotes is required to reduce the entropy barriers associated with the looping.