Figure 8. Molecular packing in the crystals of H206A Oraicryst and WT Oraicryst.
(a) Crystal packing of H206A Oraicryst. The contents of the asymmetric unit, consisting of four complete channels, is shown. Each channel is colored a unique color and shown in ribbon representation. The channels interact with one another via coiled-coil interactions between their M4-ext helices. (b) Packing of WT Oraicryst in the crystal, showing the contents of the asymmetric unit, depicted analogously to a).
Figure 8—figure supplement 1. M4-ext helices and subunit comparisons.
(a) Close-up view of a coiled-coil interaction between two M4-ext helices of the blue- and green-colored channels in the asymmetric unit of H206A Oraicryst (from Figure 7A). Ile316 and Leu319, which form the hydrophobic interface of the coiled-coil interaction on each of the M4-ext helices, are drawn as gray sticks for reference. (b) Analogous coiled-coil interaction between two M4-ext helices of the blue- and green-colored channels in the asymmetric unit of WT Oraicryst (from Figure 7B). (c) Coiled-coil interaction of two paired M4-ext helices observed in the quiescent conformation, which occurs between adjacent subunits of the same channel (from Figure 1, PDB ID 4HKR). (d) Superposition of the 24 individual subunits (from four hexameric channels) of H206A Oraicryst within the asymmetric unit, shown in Cα representation.