cooperative retraction of bundled type iv pili enables nanonewton force generation合作捆绑iv型菌毛的收缩使nanonewton力的一代.pdfVIP

PLoS BIOLOGY Cooperative Retraction of Bundled Type IV Pili Enables Nanonewton Force Generation 1 ˆ 2 3 3 1* Nicolas Biais , Benoıt Ladoux , Dustin Higashi , Magdalene So , Michael Sheetz ` ` ´ 1 Department of Biological Sciences, Columbia University, New York, New York, United States of America, 2 Matiere et Systemes Complexes, CNRS UMR7057/Universite Paris 7, ˆ Batiment Condorcet, 75205 Paris cedex 13, France, 3 Department of Immunobiology, BIO5 Institute, University of Arizona, Tucson, Arizona, United States of America The causative agent of gonorrhea, Neisseria gonorrhoeae, bears retractable filamentous appendages called type IV pili (Tfp). Tfp are used by many pathogenic and nonpathogenic bacteria to carry out a number of vital functions, including DNA uptake, twitching motility (crawling over surfaces), and attachment to host cells. In N. gonorrhoeae, Tfp binding to epithelial cells and the mechanical forces associated with this binding stimulate signaling cascades and gene expression that enhance infection. Retraction of a single Tfp filament generates forces of 50–100 piconewtons, but nothing is known, thus far, on the retraction force ability of multiple Tfp filaments, even though each bacterium expresses multiple Tfp and multiple bacteria interact during infection. We designed a micropillar assay system to measure Tfp retraction forces. This system consists of an array of force sensors made of elastic pillars that allow quantification of retraction forces from adherent N. gonorrhoeae bacteria. Electron microscopy and fluoresce