Figure 6.

The Y-model of the FtsLB complex.A, initial model. The model has the same transmembrane region of the original I-model. The coiled-coil region was modeled as a pair of two-stranded coiled-coil domains, each containing one FtsL and one FtsB helix. The modeling is based on the same set of side-chain contacts between FtsB and FtsL inferred by the coevolutionary analysis used to derive the I-model. Colored in orange is the CCD region. Spheres: lipid headgroup phosphate P atoms. B, four frames of the trajectory of a 400 ns molecular dynamic run of the Y-model. The transmembrane and coiled-coil regions remain relatively stable during the entire trajectory. The helices tend to break and occasionally unfold in correspondence of a predicted hinge near the CCD region (orange). The RMSD analysis of all three replica runs is reported in Fig. S6 and Table S3. CCD, constriction control domain.