Figure 1.
Fig. 1. Crystal structure of B. suis pVirB8. (A) Sequence
alignment of VirB8 proteins and secondary structure assignment.
Amino acids of four representative homologs were aligned, from
B. suis (B.sVirB8), A. tumefaciens (A.tVirB8, 21% identical to
B.sVirB8), H. pylori Cag [H.pCag10 (HP0530, 14% identity], and
ComB [H.pComB8 (HP0030), 18% identity] systems (38). Strictly
conserved, strongly conserved, and conserved residues are marked
in red, magenta, and light pink, respectively. The modeled
region (residues 97-188 and 191-234) is shown as a gray line
above the sequence for nonregular structure or as cyan boxes and
yellow arrows for -helices and -strands,
respectively. Green dots mark residues involved in VirB8 self
association. Purple stars indicate residues mutated in previous
functional studies. (B) Overall fold of pVirB8. Secondary
structure representation and labels are as in A. (C) Structure
of NTF2, most similar fold to pVirB8. Boxes mark the two major
points of difference between the NTF2 and pVirB8 fold, the
addition of 4 (blue box), and the
loss of two strands (red box). (D)
Surface representation of VirB8 coloring side chains by degree
of conservation, as shown in A. Orientation is as in B. (E)
pVirB8 dimer. Both monomers are shown in ribbon representation
with the monomer on the left shown as in B but turned 90°
clockwise. The other monomer is in gray. Ile-112 and Tyr-120 are
shown in stick representation and colored in magenta and green,
respectively. (F) Top-down view of pVirB8 dimer showing side
chains involved in interface as marked in A. For clarity, one
pVirB8 chain is colored gray, and the other is colored as in B.
Residues at the interface are in stick representation,
color-coded in green, and labeled. The figure was produced by
using PYMOL, http://pymol.sourceforge.net.
-helices and 
-strands,
respectively. Green dots mark residues involved in VirB8 self
association. Purple stars indicate residues mutated in previous
functional studies. (B) Overall fold of pVirB8. Secondary
structure representation and labels are as in A. (C) Structure
of NTF2, most similar fold to pVirB8. Boxes mark the two major
points of difference between the NTF2 and pVirB8 fold, the
addition of 
90°
clockwise. The other monomer is in gray. Ile-112 and Tyr-120 are
shown in stick representation and colored in magenta and green,
respectively. (F) Top-down view of pVirB8 dimer showing side
chains involved in interface as marked in A. For clarity, one
pVirB8 chain is colored gray, and the other is colored as in B.
Residues at the interface are in stick representation,
color-coded in green, and labeled. The figure was produced by
using PYMOL, http://pymol.sourceforge.net.