Fig. 2.
Comparison of the helical packing of (A and B) the C. crescentus tad pilus (PDB ID: 8U1K) with archaeal T4Ps (C and D) S. islandicus (PDB ID: 6NAV) and (E and F) S. solfataricus (PDB ID: 6W8X). The interacting subunits are connected by dashed lines with the interface area (in Å2) indicated between subunits. In all three cases, subunit S0 interacts with subunits S1, S3, S4, and S7 with similar interfacial areas revealing the similar packing of tad and archaeal T4P. Compared to the other archaeal T4P, subunit S0 has a larger interface with subunits S3 and S10 in tad, due to the curved helix of the tad pilin and the slight difference in the helical symmetry.