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Structure and oligomerization of the PilC type IV pilus biogenesis protein from Thermus thermophilus

DOI: 10.1002/prot.22720 DOI Help
PMID: 20455262 PMID Help

Authors: Vijaykumar Karuppiah (University of Manchester) , Darin Hassan (University of Manchester) , Muhammad Saleem (University of Manchester) , Jeremy Derrick (The University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Proteins: Structure, Function, And Bioinformatics , VOL 78 (9) , PAGES 2049 - 2057

State: Published (Approved)
Published: March 2010

Abstract: Type IV pili are expressed from a wide variety of Gram-negative bacteria and play a major role in host cell adhesion and bacterial motility. PilC is one of at least a dozen different proteins that are implicated in Type IV pilus assembly in Thermus thermophilus and a member of a conserved family of integral inner membrane proteins which are components of the Type II secretion system (GspF) and the archeal flagellum. PilC/GspF family members contain repeats of a conserved helix-rich domain of around 100 residues in length. Here, we describe the crystal structure of one of these domains, derived from the N-terminal domain of Thermus thermophilus PilC. The N-domain forms a dimer, adopting a six helix bundle structure with an up-down-up-down-up-down topology. The monomers are related by a rotation of 170°, followed by a translation along the axis of the final -helix of approximately one helical turn. This means that the regions of contact on helices 5 and 6 in each monomer are overlapping, but different. Contact between the two monomers is mediated by a network of hydrophobic residues which are highly conserved in PilC homologs from other Gram-negative bacteria. Site-directed mutagenesis of residues at the dimer interface resulted in a change in oligomeric state of PilC from tetramers to dimers, providing evidence that this interface is also found in the intact membrane protein and suggesting that it is important to its function.

Journal Keywords: Gel; Crystallography; X-Ray; Escherichia; Fimbriae; Hydrogen; Models; Molecular; Mutagenesis; Site-Directed; Protein; Secondary; Protein; Tertiary; Recombinant; Thermus thermophilus

Subject Areas: Biology and Bio-materials

Diamond Offline Facilities: Membrane Protein Laboratory (MPL)
Instruments: I04-Macromolecular Crystallography

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