4QS4

Crystal Structure of CofB from Enterotoxigenic Escherichia coli

Summary for 4QS4

• Entry DOI: 10.2210/pdb4qs4/pdb
• Descriptor: CofB, GLYCEROL, SULFATE ION, ... (4 entities in total)
• Functional Keywords: type iv pilin fold, cell adhesion
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 54779.64

Authors

Kolappan, S.,Craig, L. (deposition date: 2014-07-02, release date: 2015-06-03, Last modification date: 2015-11-11)

Primary citation

Kolappan, S.,Ng, D.,Yang, G.,Harn, T.,Craig, L.
Crystal Structure of the Minor Pilin CofB, the Initiator of CFA/III Pilus Assembly in Enterotoxigenic Escherichia coli.
J.Biol.Chem., 290:25805-25818, 2015

PubMed Abstract: Type IV pili are extracellular polymers of the major pilin subunit. These subunits are held together in the pilus filament by hydrophobic interactions among their N-terminal α-helices, which also anchor the pilin subunits in the inner membrane prior to pilus assembly. Type IV pilus assembly involves a conserved group of proteins that span the envelope of Gram-negative bacteria. Among these is a set of minor pilins, so named because they share their hydrophobic N-terminal polymerization/membrane anchor segment with the major pilins but are much less abundant. Minor pilins influence pilus assembly and retraction, but their precise functions are not well defined. The Type IV pilus systems of enterotoxigenic Escherichia coli and Vibrio cholerae are among the simplest of Type IV pilus systems and possess only a single minor pilin. Here we show that the enterotoxigenic E. coli minor pilins CofB and LngB are required for assembly of their respective Type IV pili, CFA/III and Longus. Low levels of the minor pilins are optimal for pilus assembly, and CofB can be detected in the pilus fraction. We solved the 2.0 Å crystal structure of N-terminally truncated CofB, revealing a pilin-like protein with an extended C-terminal region composed of two discrete domains connected by flexible linkers. The C-terminal region is required for CofB to initiate pilus assembly. We propose a model for CofB-initiated pilus assembly with implications for understanding filament growth in more complex Type IV pilus systems as well as the related Type II secretion system.

PubMed: 26324721
DOI: 10.1074/jbc.M115.676106

Experimental method

X-RAY DIFFRACTION (2 Å)