Cooperative Gating and Spatial Organization of Membrane Proteins through Elastic Interactions
Figure 6
Elastic Interactions Tightly Couple Conformational Change with Protein Dimerization
Diffusing MscL proteins are considered dimerized when they are close enough that they attract with an energy greater than kBT. At high areal density, the net attractive closed–closed interaction is sufficient to dimerize the two channels part of the time. As the areal density decreases, the closed–closed interaction is not strong enough to dimerize the two channels—now dimerization only happens at higher tensions after both channels have switched to the open conformation. As the areal density decreases further, the open–open interaction is no longer strong enough to overcome entropy. This loss of dimerization is amplified by the fact that the open–open interaction is weaker at higher tensions (see Figure 2). The white dashed lines roughly indicate the range of areal densities for which dimerization probability and open channel probability are equal to each other (see Figure 4).