（奈瑟氏球菌落及放射性菌毛的免疫熒光圖片 來源：science daily）
亞利桑那大學(xué)和哥倫比亞大學(xué)的科學(xué)家最近研究發(fā)現(xiàn)細(xì)菌的菌毛“力大無比”,，可以移動(dòng)自身質(zhì)量十萬倍的物體,。
研究人員通過對淋病奈瑟氏球菌（生物谷注：Neisseria gonorrhoeae）實(shí)驗(yàn)，一束菌毛收縮時(shí)的力量可達(dá)到單跟菌毛的十多倍,。這種驅(qū)動(dòng)收縮的分子馬達(dá)是已知?jiǎng)恿ψ顝?qiáng)的納米生物馬達(dá)。通過對菌毛的研究可以幫助解決各種致病菌的治療難題,。這項(xiàng)研究的論文發(fā)表在最新一期的《公共圖書館 生物學(xué)》上面,。（生物谷編譯）
生物谷推薦原始出處：
doi:10.1371/journal.pbio.0060087 （PLoS Biology ）April 15, 2008
Cooperative Retraction of Bundled Type IV Pili Enables Nanonewton Force Generation
Nicolas Biais1, Benoît Ladoux2, Dustin Higashi3, Magdalene So3, Michael Sheetz1*
1 Department of Biological Sciences, Columbia University, New York, New York, United States of America, 2 Matière et Systèmes Complexes, CNRS UMR7057/Université Paris 7, Bâtiment 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 fluorescence microscopy were used in combination with this novel assay to assess the structures of Tfp. We show that Tfp can form bundles, which contain up to 8–10 Tfp filaments, that act as coordinated retractable units with forces up to 10 times greater than single filament retraction forces. Furthermore, single filament retraction forces are transient, whereas bundled filaments produce retraction forces that can be sustained. Alterations of noncovalent protein–protein interactions between Tfp can inhibit both bundle formation and high-amplitude retraction forces. Retraction forces build over time through the recruitment and bundling of multiple Tfp that pull cooperatively to generate forces in the nanonewton range. We propose that Tfp retraction can be synchronized through bundling, that Tfp bundle retraction can generate forces in the nanonewton range in vivo, and that such high forces could affect infection.
