Figure 7: Superposition of right-handed and left-handed structural ensembles. | Nature Communications

Figure 7: Superposition of right-handed and left-handed structural ensembles.

From: High-resolution structure of the Shigella type-III secretion needle by solid-state NMR and cryo-electron microscopy

Figure 7

The 10 top-ranking models produced by the hybrid structure determination approach considering (a) a right-handed helix and (b) a left-handed helix. The basic tetramer formed by the symmetric subunits (i, orange), (i+5, light green), (i+6, dark green) and (i+11, pink) is presented and the N and C termini are indicated. The relative position of protein subunits is explained schematically in the top-left corner of a and b for the two arrangements. In a right-handed helix, the subunit (i+5), closer to (i) in terms of axial translation, is located to the left of (i) while subunit (i+6), further away from (i) is located to the right. Blue lines connect successive subunits as in Fig. 6. The right-handed ensemble shows sharper convergence compared with the left-handed ensemble, presents less NMR constraint violations and has a more favourable full-atom Rosetta energy, unequivocally identifying it as the correct handedness.

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