How gene colocalization can be optimized by tuning the diffusion constant of transcription factors

We introduce an analytical model which shows quantitatively that gene colocalization significantly accelerates the association of transcriptions factors (TFs) with their target site on DNA. This model takes into account the influence of conformational fluctuations of TFs on reactivity, and shows that the benefit due to colocalization, highlighted by Kolesov et al. (Proc. Natl. Acad. Sci. U.S.A., 104 (2007) 13948), can be further optimized by tuning the diffusion coefficient of TFs. This diffusion optimized colocalization mechanism is robust and compatible with available experimental data, and could help understanding the observed gene transcription efficiency.