Figure 2

Allosteric protein-protein interaction.

PMF of a TFAM dimer as a function of the surface-to-surface distance d for a homogeneous AT (blue) and GC (red) DNA molecule. The green line corresponds to the average of the two profiles. The minimum of all three profiles is located at d₀ = 3 bp. Insets schematically show the role of thermally induced base pair openings in dimer formation. (i) For d > 40 bp the two proteins practically do not feel the presence of each other. (ii) For d < 20 bp thermally induced spontaneous base pair openings create a tunnel of partially open base pairs that connects the two proteins. This produces an unbalance force that drives proteins collapse. (iii) For d < 10 bp the area between the two proteins is completely melted thereby creating a flexible hinge that increases DNA's flexibility.