Bacillus subtilis Spore Inner Membrane Proteome

The endospore is the dormant form of Bacillus subtilis and many other Firmicutes. By sporulation, these spore formers can survive very harsh physical and chemical conditions. Yet, they need to go through germination to return to their growing form. The spore inner membrane (IM) has been shown to play an essential role in triggering the initiation of germination. In this study, we isolated the IM of bacterial spores, in parallel with the isolation of the membrane of vegetative cells. With the use of GeLC–MS/MS, over 900 proteins were identified from the B. subtilis spore IM preparations. By bioinformatics-based membrane protein predictions, ca. one-third could be predicted to be membrane-localized. A large number of unique proteins as well as proteins common to the two membrane proteomes were identified. In addition to previously known IM proteins, a number of IM proteins were newly identified, at least some of which are likely to provide new insights into IM physiology, unveiling proteins putatively involved in spore germination machinery and hence putative germination inhibition targets.芽孢（endospore）是枯草芽孢杆菌（Bacillus subtilis）及诸多其他厚壁菌门（Firmicutes）微生物的休眠体形式。产芽孢微生物可通过芽孢形成（sporulation）过程，在极端严苛的物理与化学条件下存活；但它们需经历芽孢萌发（germination）过程，才能恢复至营养生长状态。已有研究证实，芽孢内膜（inner membrane, IM）在触发芽孢萌发起始环节中发挥着不可或缺的核心作用。本研究中，我们同步分离了细菌芽孢的内膜与营养体细胞（vegetative cells）的细胞膜。借助GeLC–MS/MS技术，我们在枯草芽孢杆菌芽孢内膜的制备样品中鉴定出了超过900种蛋白质。通过基于生物信息学的膜蛋白预测分析，约三分之一的蛋白质可被预测定位于膜区域。本研究共鉴定出大量独有蛋白质，以及两类膜蛋白质组（proteomes）共有的蛋白质。除此前已报道的内膜蛋白外，我们还新发现了多种内膜蛋白；其中至少部分蛋白有望为内膜生理学研究提供全新视角，同时揭示了潜在参与芽孢萌发机制的蛋白质，进而为萌发抑制靶点的筛选提供了潜在候选对象。