Cryoelectron Microscopy Reconstructions of the Pseudomonas aeruginosa and Neisseria gonorrhoeae Type IV Pili at Sub-nanometer Resolution

Abstract

We report here cryoelectron microscopy reconstructions of type IV pili (T4P) from two important human pathogens, Pseudomonas aeruginosa and Neisseria gonorrhoeae, at ∼ 8 and 5 Å resolution, respectively. The two structures reveal distinct arrangements of the pilin globular domains on the pilus surfaces, which impart different helical parameters, but similar packing of the conserved N-terminal α helices, α1, in the filament core. In contrast to the continuous α helix seen in the X-ray crystal structures of the P. aeruginosa and N. gonorrhoeae pilin subunits, α1 in the pilus filaments has a melted segment located between conserved helix-breaking residues Gly14 and Pro22, as seen for the Neisseria meningitidis T4P. Using mutagenesis we show that Pro22 is critical for pilus assembly, as are Thr2 and Glu5, which are positioned to interact in the hydrophobic filament core. These structures provide a framework for understanding T4P assembly, function, and biophysical properties.

Functional reconstitution of the type IVa pilus assembly system from enterohaemorrhagic Escherichia coli

“…Each subunit is related to an adjacent subunit by, on average, a ~11.2 Å axial rise and ~96.0° azimuthal rotation, forming a 1‐start right‐handed helix, although these parameters are quite variable in PpdD. This symmetry is very typical for Type IV pili, such as those from P. aeruginosa (Wang et al , ), N. gonorrhoeae (Wang et al , ) and N. meningitidis (Kolappan et al , ) (Table ). The symmetry of PpdD pili differs from that of PulG pseudopili assembled by the same T2SS, which showed ~10.2 Å axial rise and 83.2° of twist (Lopez‐Castilla et al , ).…”

Monoderm bacteria: the new frontier for type IV pilus biology

“…). Recent cryo‐EM reconstructions of several Tfp revealed that the filaments are right‐handed helical polymers of pilins held together by extensive hydrophobic interactions between their α1 helices, which run approximately parallel to each other within the filament core (Kolappan et al , ; Wang et al , ). Extensive sequence conservation in α1N (Fig.…”

Twitch or swim: towards the understanding of prokaryotic motion based on the type IV pilus blueprint

“…Pilins and archaellins share a characteristic 'lollipop' shape consisting of a hydrophobic N-terminal kinked α-helix followed by a C-terminal β-strand rich globular domain (Figure 2) (Braun et al, 2016;Kolappan et al, 2016;Poweleit et al, 2016;Daum et al, 2017;Wang et al, 2017). Differences in the sizes of individual monomers lead to variations in the filament packing and diameters of the assembled filaments (Braun et al, 2016;Kolappan et al, 2016;Poweleit et al, 2016;Daum et al, 2017;Wang et al, 2017).…”

“…Differences in the sizes of individual monomers lead to variations in the filament packing and diameters of the assembled filaments (Braun et al, 2016;Kolappan et al, 2016;Poweleit et al, 2016;Daum et al, 2017;Wang et al, 2017). The central core of the filament is formed from bundles of the N-terminal α-helices of individual monomers (Figure 2).…”