Searching fast for a target on a DNA without falling to traps

TL;DR

This paper proposes a theoretical mechanism enabling regulatory proteins to rapidly find specific DNA target sites despite the presence of non-specific traps, balancing speed and stability in genomic regulation.

Contribution

A simple, robust mechanism is introduced that allows proteins to locate target sites quickly without falling into traps, even with DNA sequence disorder.

Findings

Mechanism effectively resolves the speed-stability paradox.

Robust against generic DNA sequence disorder.

Does not require specially designed target sites.

Abstract

Genomic expression depends critically both on the ability of regulatory proteins to locate specific target sites on a DNA within seconds and on the formation of long lived (many minutes) complexes between these proteins and the DNA. Equilibrium experiments show that indeed regulatory proteins bind tightly to their target site. However, they also find strong binding to other non-specific sites which act as traps that can dramatically increase the time needed to locate the target. This gives rise to a conflict between the speed and stability requirements. Here we suggest a simple mechanism which can resolve this long-standing paradox by allowing the target sites to be located by proteins within short time scales even in the presence of traps. Our theoretical analysis shows that the mechanism is robust in the presence of generic disorder in the DNA sequence and does not require a specially designed target site.