10月3日出版的《科學(xué)》（Science）雜志刊登了一項新發(fā)現(xiàn),，倫敦皇家學(xué)院和紐斯卡爾大學(xué)科學(xué)家組成的研究小組首次觀察到了細(xì)菌細(xì)胞中的“危險指揮中心”,，該中心能夠發(fā)出行動命令，使得細(xì)胞在受到外界壓力和危險時能夠立即采取“行動”,，避免傷害,。這一新發(fā)現(xiàn)將有助于科學(xué)家們進一步認(rèn)識微生物的基本生存機理，了解為什么有些微生物生命力那么旺盛,。
當(dāng)細(xì)菌細(xì)胞發(fā)現(xiàn)自己處于某種危險狀況下時,，比如當(dāng)所處環(huán)境的溫度或含鹽量會威脅到細(xì)菌的生存時，細(xì)胞表面會發(fā)出一種危險警告信號,，并將信號傳導(dǎo)到細(xì)胞內(nèi)部,，使細(xì)胞產(chǎn)生應(yīng)激反應(yīng)。但這種應(yīng)激反應(yīng)的過程非常復(fù)雜，科學(xué)家們以前從來沒有觀察到過這一過程,。
聯(lián)合研究小組通過電子顯微鏡成像技術(shù),，觀察到在細(xì)菌細(xì)胞內(nèi)的“危險指揮中心”就是一個大分子，并取名叫“壓力分子”（stressosome）,，每個細(xì)胞大約有20個壓力分子,，這些分子在細(xì)胞內(nèi)到處游動。當(dāng)細(xì)胞處于危險情況時,，壓力分子會接收到警告信號,，當(dāng)收到警告信號后，大壓力分子就會分解一些應(yīng)激蛋白,，應(yīng)激蛋白會誘導(dǎo)一系列的連鎖信號反應(yīng),，連鎖反應(yīng)導(dǎo)致細(xì)胞內(nèi)新產(chǎn)生150多種蛋白質(zhì)，這些新產(chǎn)生的蛋白質(zhì)使得細(xì)胞能夠適應(yīng)新環(huán)境,，并恢復(fù)活力從而生存下來,。
研究小組認(rèn)為，這些特殊蛋白的產(chǎn)生意味著轉(zhuǎn)錄它們的特殊基因被“開啟”了,，整個過程發(fā)生得很快,，這也說明細(xì)菌細(xì)胞具有快速應(yīng)激反應(yīng)能力，只有“快”才能存活下來,。
研究小組下一步的工作計劃是,，利用目前世界上研究生物分子結(jié)構(gòu)的最新型高分辨率低溫電子顯微鏡技術(shù)觀察這些壓力分子的三維結(jié)構(gòu)，了解它們的氨基酸組分,。（生物谷Bioon.com）
生物谷推薦原始出處：
Science,，Vol. 322. no. 5898, pp. 92 - 96，Jon Marles-Wright,，Richard J. Lewis
Molecular Architecture of the "Stressosome," a Signal Integration and Transduction Hub
Jon Marles-Wright,Tim Grant, Olivier Delumeau,Gijs van Duinen, Susan J. Firbank, Peter J. Lewis, James W. Murray, Joseph A. Newman, Maureen B. Quin, Paul R. Race, Alexis Rohou, Willem Tichelaar, Marin van Heel, Richard J. Lewis
A commonly used strategy by microorganisms to survive multiple stresses involves a signal transduction cascade that increases the expression of stress-responsive genes. Stress signals can be integrated by a multiprotein signaling hub that responds to various signals to effect a single outcome. We obtained a medium-resolution cryo–electron microscopy reconstruction of the 1.8-megadalton "stressosome" from Bacillus subtilis. Fitting known crystal structures of components into this reconstruction gave a pseudoatomic structure, which had a virus capsid–like core with sensory extensions. We suggest that the different sensory extensions respond to different signals, whereas theconserved domains in the core integrate the varied signals. The architecture of the stressosome provides the potential for cooperativity, suggesting that the response could be tuned dependent on the magnitude of chemophysical insult.
