沙雷菌[圖片來(lái)自：(Credit: Gross L (2006) Cultivating Bacteria's Taste for Toxic Waste. PLoS Biol 4(8): e282. doi:10.1371/journal.pbio.0040282)]
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東安格利亞大學(xué)(University of East Anglia)科學(xué)家們的一項(xiàng)突破性的發(fā)現(xiàn)使得利用細(xì)菌產(chǎn)生能量邁出重要一步,。
2011年5月23日發(fā)表在 PNAS 雜志上的一篇研究論文第一次顯示能讓細(xì)菌細(xì)胞轉(zhuǎn)移電荷的蛋白的精確分子結(jié)構(gòu)。這一發(fā)現(xiàn)意味著科學(xué)家們現(xiàn)在能夠著手開(kāi)發(fā)一些方法將細(xì)菌直接固定到電極上,，從而創(chuàng)造有效的微生物燃料電池或“生物電池”,。該研究進(jìn)展也可能加快基于微生物的能夠清除石油或鈾污染的試劑的開(kāi)發(fā),，以及以人類或動(dòng)物垃圾提供動(dòng)力的燃料電池的開(kāi)發(fā),。
東安格利亞大學(xué)生物科學(xué)學(xué)院的Tom Clarke博士說(shuō),，“這是一項(xiàng)令人興奮的進(jìn)展，有助于我們理解一些細(xì)菌種類怎樣將電子從細(xì)胞外部傳遞到內(nèi)部,。”
“確定出那些參與這個(gè)過(guò)程的關(guān)鍵蛋白的精確分子結(jié)構(gòu),，對(duì)于將這些微生物作為未來(lái)可行的電源而言，是一個(gè)關(guān)鍵性的步驟,。”
該研究項(xiàng)目得到生物技術(shù)和生物科學(xué)研究理事會(huì) (Biotechnology and Biological Sciences Research Council, BBSRC)和美國(guó)能源部的資金資助,。東安格利亞大學(xué)的Clarke博士、David Richardson教授和Julea Butt教授負(fù)責(zé)該項(xiàng)目的研究,，同時(shí)也得到美國(guó)西北太平洋國(guó)家實(shí)驗(yàn)室同行的合作與支持,。
這個(gè)研究小組2009年發(fā)表在PNAS上的早期研究表明在無(wú)氧的環(huán)境中細(xì)菌的存活機(jī)制，即通過(guò)構(gòu)建穿過(guò)細(xì)胞壁的電線(electrical wire),，并與礦物質(zhì)接觸---這個(gè)過(guò)程稱為鐵呼吸或者“巖石呼吸”(breathing rock),。
在這項(xiàng)最新的研究當(dāng)中，科學(xué)家們使用X射線結(jié)晶學(xué)來(lái)揭示出附著在沙雷菌(Shewanella oneidensis)細(xì)胞表面的蛋白質(zhì)的分子結(jié)構(gòu),，而細(xì)菌就是通過(guò)這些蛋白傳遞電子,。\\生命科學(xué)論壇\\ towersimper
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Journal Reference:Structure of a bacterial cell surface decaheme electron conduit.
Thomas A. Clarke, Marcus J. Edwards, Andrew J. Gates, Andrea Hall, Gaye F. White, Justin Bradley, Catherine L. Reardon, Liang Shi, Alexander S. Beliaev, Matthew J. Marshall, Zheming Wang, Nicholas J. Watmough, James K. Fredrickson, John M. Zachara, Julea N. Butt and David J. Richardson.
Abstract
Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of trans-outer-membrane electron transfer conduits. The cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or participating in extracellular intercytochrome electron exchange along “nanowire” appendages. We present a 3.2-? crystal structure of one of these decaheme cytochromes, MtrF, that allows the spatial organization of the 10 hemes to be visualized for the first time. The hemes are organized across four domains in a unique crossed conformation, in which a staggered 65-? octaheme chain transects the length of the protein and is bisected by a planar 45-? tetraheme chain that connects two extended Greek key split β-barrel domains. The structure provides molecular insight into how reduction of insoluble substrate (e.g., minerals), soluble substrates (e.g., flavins), and cytochrome redox partners might be possible in tandem at different termini of a trifurcated electron transport chain on the cell surface.
Published online before print? May 23, 2011, doi:10.1073/pnas.1017200108PNAS May 23, 2011
