Fig. 5.

Structural characterization of the nozzle protein. a Electrostatic potential surfaces of the interacting region between the gp11 adaptor (top) and gp12 nozzle (bottom). b Ribbon representation of gp12 protein structure in the tail complex in orange, with the four closing gates highlighted in dark blue. Diameters of the channel at each of the gates when measured from Cα to Cα are as follows: gate 1, 18.3 Å; gate 2, 8.6 Å (from carbonyl O to carbonyl O); gate 3, 13.8 Å; and gate 4, 23 Å. c Detail of the gp12 closing gate 2, with the map density shown in mesh and the protein atomic model in orange ribbon. Left, lateral view; Right, axial view