10月3日出版的《科学》(Science)杂志刊登了一项新发现,伦敦皇家学院和纽斯卡尔大学科学家组成的研究小组首次观察到了细菌细胞中的“危险指挥中心”,该中心能够发出行动命令,使得细胞在受到外界压力和危险时能够立即采取“行动”,避免伤害。这一新发现将有助于科学家们进一步认识微生物的基本生存机理,了解为什么有些微生物生命力那么旺盛。
当细菌细胞发现自己处于某种危险状况下时,比如当所处环境的温度或含盐量会威胁到细菌的生存时,细胞表面会发出一种危险警告信号,并将信号传导到细胞内部,使细胞产生应激反应。但这种应激反应的过程非常复杂,科学家们以前从来没有观察到过这一过程。
联合研究小组通过电子显微镜成像技术,观察到在细菌细胞内的“危险指挥中心”就是一个大分子,并取名叫“压力分子”(stressosome),每个细胞大约有20个压力分子,这些分子在细胞内到处游动。当细胞处于危险情况时,压力分子会接收到警告信号,当收到警告信号后,大压力分子就会分解一些应激蛋白,应激蛋白会诱导一系列的连锁信号反应,连锁反应导致细胞内新产生150多种蛋白质,这些新产生的蛋白质使得细胞能够适应新环境,并恢复活力从而生存下来。
研究小组认为,这些特殊蛋白的产生意味着转录它们的特殊基因被“开启”了,整个过程发生得很快,这也说明细菌细胞具有快速应激反应能力,只有“快”才能存活下来。
研究小组下一步的工作计划是,利用目前世界上研究生物分子结构的最新型高分辨率低温电子显微镜技术观察这些压力分子的三维结构,了解它们的氨基酸组分。(生物谷Bioon.com)
生物谷推荐原始出处:
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.