3HTL

Structure of the Corynebacterium diphtheriae major pilin SpaA points to a modular pilus assembly with stabilizing isopeptide bonds

Summary for 3HTL

• Entry DOI: 10.2210/pdb3htl/pdb
• Related: 3HR6
• Descriptor: Putative surface-anchored fimbrial subunit, CALCIUM ION, SODIUM ION, ... (4 entities in total)
• Functional Keywords: isopeptide bond, ig-like fold, cell wall, peptidoglycan-anchor, structural protein, cell adhesion
• Biological source: Corynebacterium diphtheriae
• Total number of polymer chains: 1
• Total formula weight: 47130.10

Authors

Kang, H.J.,Paterson, N.G.,Gaspar, A.H.,Ton-That, H.,Baker, E.N. (deposition date: 2009-06-11, release date: 2009-09-15, Last modification date: 2024-11-20)

Primary citation

Kang, H.J.,Paterson, N.G.,Gaspar, A.H.,Ton-That, H.,Baker, E.N.
The Corynebacterium diphtheriae shaft pilin SpaA is built of tandem Ig-like modules with stabilizing isopeptide and disulfide bonds
Proc.Natl.Acad.Sci.USA, 106:16967-16971, 2009

PubMed Abstract: Cell-surface pili are important virulence factors that enable bacterial pathogens to adhere to specific host tissues and modulate host immune response. Relatively little is known about the structure of Gram-positive bacterial pili, which are built by the sortase-catalyzed covalent crosslinking of individual pilin proteins. Here we report the 1.6-A resolution crystal structure of the shaft pilin component SpaA from Corynebacterium diphtheriae, revealing both common and unique features. The SpaA pilin comprises 3 tandem Ig-like domains, with characteristic folds related to those typically found in non-pilus adhesins. Whereas both the middle and the C-terminal domains contain an intramolecular Lys-Asn isopeptide bond, previously detected in the shaft pilins of Streptococcus pyogenes and Bacillus cereus, the middle Ig-like domain also harbors a calcium ion, and the C-terminal domain contains a disulfide bond. By mass spectrometry, we show that the SpaA monomers are cross-linked in the assembled pili by a Lys-Thr isopeptide bond, as predicted by previous genetic studies. Together, our results reveal that despite profound dissimilarities in primary sequences, the shaft pilins of Gram-positive pathogens have strikingly similar tertiary structures, suggesting a modular backbone construction, including stabilizing intermolecular and intramolecular isopeptide bonds.

PubMed: 19805181
DOI: 10.1073/pnas.0906826106

Experimental method

X-RAY DIFFRACTION (1.8 Å)