(A) Interfaces between the HO BMC-TS1 trimer (red hues) and the BMC-H hexamers (alternating grey/light blue) viewed from the outside of the shell. The pseudohexameric BMC-TS trimer forms two types of interfaces with BMC-H subunits (indicated). Straight/bent lines indicate the planar and bent hexamer interface; the positions of one neighboring BMC-P and BMC-T are indicated.
(B, C) Detailed views of the two interfaces (B, interface 1; C, interface 2). Dashed lines indicate hydrogen bonds and salt bridges. Residues discussed in the text are labeled. See also Figure S1.