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Single Molecule Force Spectroscopy Reveals Two-Domain Binding Mode of Pilus‑1 Tip Protein RrgA of <i>Streptococcus pneumoniae</i> to Fibronectin

By Tanja D. Becke (4747143), Stefan Ness (4747146), Raimund Gürster (4747149), Arndt F. Schilling (172417), Anne-Marie di Guilmi (4747140), Stefanie Sudhop (4747152), Markus Hilleringmann (42464) and Hauke Clausen-Schaumann (385574)


For host cell adhesion and invasion, surface piliation procures benefits for bacteria. A detailed investigation of how pili adhere to host cells is therefore a key aspect in understanding their role during infection. <i>Streptococcus pneumoniae</i> TIGR 4, a clinical relevant serotype 4 strain, is capable of expressing pilus-1 with terminal RrgA, an adhesin interacting with host extracellular matrix (ECM) proteins. We used single molecule force spectroscopy to investigate the binding of full-length RrgA and single RrgA domains to fibronectin. Our results show that full-length RrgA and its terminal domains D3 and D4 bind to fibronectin with forces of 51.6 (full length), 52.8 (D3), and 46.2 pN (D4) at force-loading rates of around 1500 pN/s. Selective saturation of D3 and D4 binding sites on fibronectin showed that both domains can interact simultaneously with fibronectin, revealing a two-domain binding mechanism for the pilus-1 tip protein. The high off rates and the corresponding short lifetime of the RrgA Fn bond (τ = 0.26 s) may enable piliated pneumococci to form and maintain a transient contact to fibronectin-containing host surfaces and thus to efficiently scan the surface for specific receptors promoting host cell adhesion and invasion. These molecular properties could be essential for <i>S. pneumoniae</i> pili to mediate initial contact to the host cells andshared with other piliated Gram-positive bacteriafavor host invasion

Topics: Biophysics, Biochemistry, Microbiology, Cell Biology, Biotechnology, Evolutionary Biology, Developmental Biology, Cancer, Infectious Diseases, Computational Biology, Biological Sciences not elsewhere classified, Chemical Sciences not elsewhere classified, Physical Sciences not elsewhere classified, molecule force spectroscopy, pneumoniae, D 4 binding sites, TIGR, serotype 4 strain, Two-Domain Binding Mode, fibronectin-containing host surfaces, terminal domains D 3, host cell adhesion, surface piliation procures benefits, ECM, RrgA, D 4 bind, host cells, two-domain binding mechanism, invasion, Single Molecule Force Spectroscopy, host extracellular matrix
Year: 2018
DOI identifier: 10.1021/acsnano.7b07247.ls01
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Provided by: FigShare
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