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TZID:Europe/Paris
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BEGIN:VEVENT
UID:0-878@lptms.universite-paris-saclay.fr
DTSTART:20230407T110000Z
DTEND:20230407T121500Z
DTSTAMP:20230504T111920Z
URL:https://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-
 interface-seminar-albertus-viljoen/
SUMMARY:Physics-Biology interface seminar: Albertus Viljoen - Moyen Amphi\,
  Building 510\, Université Paris-Saclay Orsay - 7 Avr 23 11:00
DESCRIPTION:AFM force spectroscopy studies unravel how functional nanodomai
 ns on pathogenic bacteria drive selective recognition by host immune cells
 .\nAlbertus Viljoen (Louvain Institute of Biomolecular Science and Technol
 ogy\, UC Louvain)\nAdhesion to host cells and tissues is an important firs
 t step in infection employed by many bacterial pathogens. In mycobacteria\
 , surface hydrophobic properties and specialized receptor-ligand bonds det
 ermine how these pathogens adhere to host immune cells. We recently used f
 ast quantitative imaging (QI) atomic force microscopy (AFM) combined with 
 hydrophobic tips to quantitatively map hydrophobic properties of mycobacte
 rial pathogens\, at high spatial resolution1. We discovered that abundant 
 polar outer membrane lipids modulate the nanoscale distribution of hydroph
 obicity on the bacterial surface\, which could be modulated by treatments 
 with specific antibiotics. This led us to hypothesize that the presence of
  nanodomains enriched in specific surface molecules have a functional role
  in pathogen-host interactions. We have now found support for this hypothe
 sis by studying recognition of pathogenic mycobacteria by the pathogen rec
 ognition receptor DC-SIGN 2. By probing live mycobacteria with AFM tips mo
 dified with single tetramers of the soluble extracellular domain of DC-SIG
 N we observed that the receptor forms complexes with ligands on pathogenic
  and nonpathogenic mycobacteria. Moreover\, the complexes are mechanically
  weak\, rupturing at ~30 pN under physiological force loading rates. Howev
 er\, by relying on the specific force-extension signatures generated we co
 uld map the locations of single DC-SIGN ligands at a resolution of ~20 nm\
 , which revealed concentration of ligands into dense nanodomains on pathog
 enic mycobacteria exclusively. Upon bacteria-host cell contact\, ligand na
 nodomains induce the recruitment and clustering of DC-SIGN\, resulting in 
 mechanically stable adhesion. This work highlights the key role of cluster
 ing of both ligands on pathogenic bacteria and DC-SIGN host receptors in p
 athogen recognition\, a mechanism that might be widespread in host-pathoge
 n interactions.\n&nbsp\;\n\n 	Viljoen\, A.\, Viela\, F.\, Kremer\, L. &amp
 \; Dufrêne\, Y. F. Fast chemical force microscopy demonstrates that glyco
 peptidolipids define nanodomains of varying hydrophobicity on mycobacteria
 . Nanoscale Horiz. 5\, 944–953 (2020).\n 	Viljoen\, A. et al. Nanoscale 
 clustering of mycobacterial ligands and DC-SIGN host receptors are key det
 erminants for pathogen recognition. Sci. Adv. accepted\, (2023).\n
CATEGORIES:seminars
LOCATION:Moyen Amphi\, Building 510\, Université Paris-Saclay Orsay\, 15 R
 ue Georges Clemenceau\, orsay\, France
GEO:48.698187;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=Moyen Amphi\, Building 510\, Un
 iversité Paris-Saclay Orsay:geo:48.698187,2.181768
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