The ultrastructure of Ignicoccus: Evidence for a novel outer membrane and for intracellular vesicle budding in an archaeon
The ultrastructure of Ignicoccus: Evidence for a novel outer membrane and for intracellular vesicle budding in an archaeon
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DOI：
10.1155/2002/307480
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发表时间：
2002-03-01
期刊：
影响因子：
2.4
通讯作者：
Huber, Harald
中科院分区：
文献类型：
--
作者：
Rachel, Reinhard;Wyschkony, Irith;Huber, Harald
最近描述了一种新的极端嗜热、严格化能无机营养古菌属--嗜热古菌，（到目前为止）有三个纯培养菌株。通过在纤维素毛细管中培养并通过高压冷冻、冷冻置换和Epon包埋处理来制备用于超微结构研究的细胞。根据该方案制备的细胞一致地显示出一种新的细胞包膜结构，以前未知的间充质干细胞：细胞质膜;周质空间，具有20至400 nm的可变宽度，含有膜结合囊泡;和外鞘，约10 nm宽，类似于革兰氏阴性菌的外膜。该鞘包含三种类型的颗粒：许多紧密的、不规则堆积的单个颗粒，直径约为8 nm;直径为24 nm的孔，被微小颗粒包围，排列成直径为130 nm的环;以及多达8个颗粒的簇，每个颗粒直径为12 nm。冷冻蚀刻的细胞表现出光滑的表面，没有规则的图案，通过外鞘频繁的断裂面，表明存在外膜和S层的情况下。这项研究说明了新的复杂的架构的细胞包膜的adjacicoccus以及精心准备的超微结构调查程序的重要性。
A novel genus of hyperthermophilic, strictly chemolithotrophic archaea, Ignicoccus, has been described recently, with (so far) three isolates in pure culture. Cells were prepared for ultrastructural investigation by cultivation in cellulose capillaries and processing by high-pressure freezing, freeze-substitution and embedding in Epon. Cells prepared in accordance with this protocol consistently showed a novel cell envelope structure previously unknown among the Archaea: a cytoplasmic membrane; a periplasmic space with a variable width of 20 to 400 nm, containing membrane-bound vesicles; and an outer sheath, approximately 10 nm wide, resembling the outer membrane of gram-negative bacteria. This sheath contained three types of particles: numerous tightly, irregularly packed single particles, about 8 nm in diameter; pores with a diameter of 24 nm, surrounded by tiny particles, arranged in a ring with a diameter of 130 nm; and clusters of up to eight particles, each particle 12 nm in diameter. Freeze-etched cells exhibited a smooth surface, without a regular pattern, with frequent fracture planes through the outer sheath, indicating the presence of an outer membrane and the absence of an S-layer. The study illustrates the novel complex architecture of the cell envelope of Ignicoccus as well as the importance of elaborate preparation procedures for ultrastructural investigations.