The DNA binding activity of p53 displays reaction-diffusion kinetics

Biophys J. 2006 Jul 1;91(1):330-42. doi: 10.1529/biophysj.105.078303. Epub 2006 Apr 7.


The tumor suppressor protein p53 plays a key role in maintaining the genomic stability of mammalian cells and preventing malignant transformation. In this study, we investigated the intracellular diffusion of a p53-GFP fusion protein using confocal fluorescence recovery after photobleaching. We show that the diffusion of p53-GFP within the nucleus is well described by a mathematical model for diffusion of particles that bind temporarily to a spatially homogeneous immobile structure with binding and release rates k1 and k2, respectively. The diffusion constant of p53-GFP was estimated to be Dp53-GFP=15.4 microm2 s-1, significantly slower than that of GFP alone, DGFP=41.6 microm2 s-1. The reaction rates of the binding and unbinding of p53-GFP were estimated as k1=0.3 s-1 and k2=0.4 s-1, respectively, values suggestive of nonspecific binding. Consistent with this finding, the diffusional mobilities of tumor-derived sequence-specific DNA binding mutants of p53 were indistinguishable from that of the wild-type protein. These data are consistent with a model in which, under steady-state conditions, p53 is latent and continuously scans DNA, requiring activation for sequence-specific DNA binding.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Active Transport, Cell Nucleus / physiology
  • Binding Sites
  • Cell Nucleus / chemistry*
  • Cell Nucleus / metabolism*
  • Computer Simulation
  • DNA / chemistry*
  • DNA / metabolism*
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism
  • Diffusion
  • Kinetics
  • Models, Biological*
  • Models, Chemical
  • Protein Binding
  • Tumor Suppressor Protein p53 / chemistry*
  • Tumor Suppressor Protein p53 / metabolism*


  • DNA-Binding Proteins
  • Tumor Suppressor Protein p53
  • DNA