3S0T

Crystal structure of the CofA Type IV pilin subunit from enterotoxigenic E. coli

Summary for 3S0T

• Entry DOI: 10.2210/pdb3s0t/pdb
• Descriptor: CFA/III pilin, GLYCEROL, SODIUM ION, ... (4 entities in total)
• Functional Keywords: fiber-forming protein, pilus, colonization factor, bacterial surface, cell adhesion
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 38545.84

Authors

Kolappan, S.,Craig, L. (deposition date: 2011-05-13, release date: 2012-04-11, Last modification date: 2023-09-13)

Primary citation

Kolappan, S.,Roos, J.,Yuen, A.S.,Pierce, O.M.,Craig, L.
Structural Characterization of CFA/III and Longus Type IVb Pili from Enterotoxigenic Escherichia coli.
J.Bacteriol., 194:2725-2735, 2012

PubMed Abstract: The type IV pili are helical filaments found on many Gram-negative pathogenic bacteria, with multiple diverse roles in pathogenesis, including microcolony formation, adhesion, and twitching motility. Many pathogenic enterotoxigenic Escherichia coli (ETEC) isolates express one of two type IV pili belonging to the type IVb subclass: CFA/III or Longus. Here we show a direct correlation between CFA/III expression and ETEC aggregation, suggesting that these pili, like the Vibrio cholerae toxin-coregulated pili (TCP), mediate microcolony formation. We report a 1.26-Å resolution crystal structure of CofA, the major pilin subunit from CFA/III. CofA is very similar in structure to V. cholerae TcpA but possesses a 10-amino-acid insertion that replaces part of the α2-helix with an irregular loop containing a 3(10)-helix. Homology modeling suggests a very similar structure for the Longus LngA pilin. A model for the CFA/III pilus filament was generated using the TCP electron microscopy reconstruction as a template. The unique 3(10)-helix insert fits perfectly within the gap between CofA globular domains. This insert, together with differences in surface-exposed residues, produces a filament that is smoother and more negatively charged than TCP. To explore the specificity of the type IV pilus assembly apparatus, CofA was expressed heterologously in V. cholerae by replacing the tcpA gene with that of cofA within the tcp operon. Although CofA was synthesized and processed by V. cholerae, no CFA/III filaments were detected, suggesting that the components of the type IVb pilus assembly system are highly specific to their pilin substrates.

PubMed: 22447901
DOI: 10.1128/JB.00282-12

Experimental method

X-RAY DIFFRACTION (1.26 Å)