title: The Nanomechanical Properties of Lactococcus lactis Pili Are Conditioned by the Polymerized Backbone Pilin.
abstract: Pili produced by Lactococcus lactis subsp. lactis are putative linear structures consisting of repetitive subunits of the major pilin PilB that forms the backbone, pilin PilA situated at the distal end of the pilus, and an anchoring pilin PilC that tethers the pilus to the peptidoglycan. We determined the nanomechanical properties of pili using optical-tweezers force spectroscopy. Single pili were exposed to optical forces that yielded force-versus-extension spectra fitted using the Worm-Like Chain model. Native pili subjected to a force of 0-200 pN exhibit an inextensible, but highly flexible ultrastructure, reflected by their short persistence length. We tested a panel of derived strains to understand the functional role of the different pilins. First, we found that both the major pilin PilB and sortase C organize the backbone into a full-length organelle and dictate the nanomechanical properties of the pili. Second, we found that both PilA tip pilin and PilC anchoring pilin were not essential for the nanomechanical properties of pili. However, PilC maintains the pilus on the bacterial surface and may play a crucial role in the adhesion- and biofilm-forming properties of L. lactis.
authors.affiliation: Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France.|INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France.|CNRS, UMR5504, F-31400, Toulouse, France.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Castelain
authors.affiliation: Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France.|INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France.|CNRS, UMR5504, F-31400, Toulouse, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Duviau
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Canette
authors.affiliation: Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France.|INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France.|CNRS, UMR5504, F-31400, Toulouse, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Schmitz
authors.affiliation: Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France.|INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France.|CNRS, UMR5504, F-31400, Toulouse, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Loubière
authors.affiliation: Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France.|INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France.|CNRS, UMR5504, F-31400, Toulouse, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Cocaign-Bousquet
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Piard
authors.affiliation: Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France.|INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France.|CNRS, UMR5504, F-31400, Toulouse, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Mercier-Bonin
mesh_terms: D019881:Aminoacyltransferases / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D001696:Biomechanical Phenomena; D003546:Cysteine Endopeptidases / Q000378:metabolism; D036781:Fimbriae Proteins / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D013294:Lactococcus lactis / Q000166:cytology* / Q000378:metabolism*; D008954:Models, Biological; D058105:Polymerization
chemical_list: D001426:Bacterial Proteins; C509822:sortase C; D036781:Fimbriae Proteins; D019881:Aminoacyltransferases; D003546:Cysteine Endopeptidases