PDBsum entry 1oqw

Cell adhesion

PDB id: 1oqw

Contents

Protein chains

144 a.a. *

Waters ×282

* Residue conservation analysis

References listed in PDB file

Key reference

Title

Type IV pilin structure and assembly: X-Ray and em analyses of vibrio cholerae toxin-Coregulated pilus and pseudomonas aeruginosa pak pilin.

Authors

L.Craig, R.K.Taylor, M.E.Pique, B.D.Adair, A.S.Arvai, M.Singh, S.J.Lloyd, D.S.Shin, E.D.Getzoff, M.Yeager, K.T.Forest, J.A.Tainer.

Ref.

Mol Cell, 2003, 11, 1139-1150. [DOI no: 10.1016/S1097-2765(03)00170-9]

PubMed id

12769840

Abstract

Pilin assembly into type IV pili is required for virulence by bacterial pathogens that cause diseases such as cholera, pneumonia, gonorrhea, and meningitis. Crystal structures of soluble, N-terminally truncated pilin from Vibrio cholera toxin-coregulated pilus (TCP) and full-length PAK pilin from Pseudomonas aeruginosa reveal a novel TCP fold, yet a shared architecture for the type IV pilins. In each pilin subunit a conserved, extended, N-terminal alpha helix wrapped by beta strands anchors the structurally variable globular head. Inside the assembled pilus, characterized by cryo-electron microscopy and crystallography, the extended hydrophobic alpha helices make multisubunit contacts to provide mechanical strength and flexibility. Outside, distinct interactions of adaptable heads contribute surface variation for specificity of pilus function in antigenicity, motility, adhesion, and colony formation.

Figure 4.
Figure 4. TcpA Crystal Lattice and Structure-Based Model of TCP Filament(A) Crystal lattice showing TcpA subunits arranged in hexagonally packed fibers. The three molecules in the asymmetric unit are colored red and appear at different levels.(B) A single crystallographic fiber showing that the N-terminal α helices face the center of the fiber and have the same polarity. The three strands of the helical fiber are colored red, blue, and yellow. Two subunits are shown for each start, with the second one rotated 60° counterclockwise relative to the first and translated 17.85 Å along the fiber axis (i.e., into the page).(C) Side view of a single crystallographic fiber showing the left-handed three-start helix, fiber dimensions, and helical symmetry. Six subunits are shown in one complete turn for each helical strand of the three-start helix assembly.(D) Hydrophobic interface connecting subunits within each strand of the left-handed three-start helices. Side chains on α2 of one subunit are shown as yellow ball-and-stick representations on an orange ribbon, and side chains on α3 and α4 are shown in cyan on a green ribbon. Relevant oxygen atoms are colored red, and nitrogens are blue. In addition to the hydrophobic interactions, two hydrogen bonds link the subunits (Tyr51:OH to Leu176:O, and Thr125:OH to Leu76:O) as indicated by white spheres. The disulfide-bound cysteines are colored pink with yellow sulfur atoms.(E and F) Top view (E) and side view (F) of the structure-based TCP model derived from the symmetry determined by EM analysis and the packing arrangement seen in the crystallographic fibers. An extended α-helical tail has been added to the N terminus using the coordinates of the PAK pilin α1-N. The dimensions are shown for comparison with the crystallographic fiber in (C).

Figure 5.
Figure 5. Results of Mutational and Epitope Mapping Studies Are Consistent with the Three-Start Helix TCP Model(A) Top view of TcpA showing the location of structural (yellow) and functional (blue) residues. Pro69 (green) has both structural and functional properties.(B) Surface representation of a section of the TCP model showing that overlapping protective epitopes (Sun et al., 1997), colored off-white, map to a large surface-exposed patch on the TcpA subunit.

The above figures are reprinted by permission from Cell Press: Mol Cell (2003, 11, 1139-1150) copyright 2003.