Passive DNA shuttling

In eukaryotic cells, a variety of DNA functional interactions with nuclear elements occurs via Brownian, “passive” mechanisms. This raises the question on how DNA loci can recognize their target and be reliably shuttled to destination by diffusion. We discuss such a topic in the framework of the polymer adsorption problem, via a schematic Statistical Physics model where Brownian binding molecules mediate DNA-target interactions. In that context, we show that binding molecules can induce stable colocalization of DNA and its target (“passive shuttling”) via a switch-like process, regulated by a phase transition: DNA is shuttled to target only if the concentration/affinity of binding molecules is above a threshold value. We then illustrate the effects of genetic/chemical manipulations, e.g., DNA deletions, on the process.