Structure of the Bacterial Cellulose Ribbon and Its Assembly-Guiding Cytoskeleton by Electron Cryotomography.
Structure of the Bacterial Cellulose Ribbon and Its Assembly-Guiding Cytoskeleton by Electron Cryotomography.
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DOI：
10.1128/jb.00371-20
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发表时间：
2021-01-11
影响因子：
3.2
通讯作者：
Jensen GJ
中科院分区：
文献类型：
--
作者：
Nicolas WJ;Ghosal D;Tocheva EI;Meyerowitz EM;Jensen GJ
这项工作对微生物学界的意义是双重的。它首次提供了葡萄糖酸醋杆菌属的高分辨率近原生快照。（以前称为Komagataeibacter spp.）在纤维素带合成的过程中，在它们的天然生物膜环境中。纤维素是细菌生物膜的广泛组分，其中其优异的保水性、高拉伸强度和刚度的性质防止生物膜的脱水和机械破坏。葡萄糖酸醋杆菌属的细菌分泌结晶纤维素，其结构与植物细胞壁中发现的结构非常相似。这种高阶结构是如何产生的，人们知之甚少。我们使用低温电子断层扫描和聚焦离子束研磨的天然细菌生物膜的图像纤维素合成的Gluconacetobacter hansenii和Gluconacetobacter xylinus细菌在冷冻水合，接近天然状态。我们证实了以前的结果表明，纤维素结晶发生连续分泌沿着一侧的细胞，导致纤维素带，可以达到几微米的长度和联合收割机与其他细胞的丝带，形成一个强大的生物膜基质。我们能够在纤维素片的接近天然状态下进行直接测量。我们的研究结果还揭示了一种新的细胞骨架结构，我们将其命名为皮质带，它邻近内膜，位于纤维素从细胞中出现的位置。我们发现，这种结构不存在于其他纤维素合成细菌物种，根癌农杆菌和大肠杆菌1094，不产生有组织的纤维素带。因此，我们认为皮层带将纤维素合酶复合物保持在一条线上，以形成更高级的纤维素结构，如片状和带状。这项工作对微生物学界的意义是双重的。它首次提供了葡萄糖酸醋杆菌属的高分辨率近原生快照。（以前称为Komagataeibacter spp.）在纤维素带合成的过程中，在它们的天然生物膜环境中。它提出了一个非特征性的细胞骨架元素与纤维素合成发生的细胞侧。这代表了对结晶纤维素合成的细胞引导过程的理解向前迈进了一步，该过程专门在葡糖酸醋杆菌属中进行了研究，但仍未完全理解。此外，我们成功地尝试使用低温聚焦离子束铣削通过生物膜成像细胞在其原生环境中将推动社会使用这种工具的形态学表征的其他研究生物膜。
This work’s relevance for the microbiology community is twofold. It delivers for the first time high-resolution near-native snapshots of Gluconacetobacter spp. (previously Komagataeibacter spp.) in the process of cellulose ribbon synthesis, in their native biofilm environment. Cellulose is a widespread component of bacterial biofilms, where its properties of exceptional water retention, high tensile strength, and stiffness prevent dehydration and mechanical disruption of the biofilm. Bacteria in the genus Gluconacetobacter secrete crystalline cellulose, with a structure very similar to that found in plant cell walls. How this higher-order structure is produced is poorly understood. We used cryo-electron tomography and focused-ion-beam milling of native bacterial biofilms to image cellulose-synthesizing Gluconacetobacter hansenii and Gluconacetobacter xylinus bacteria in a frozen-hydrated, near-native state. We confirm previous results suggesting that cellulose crystallization occurs serially following its secretion along one side of the cell, leading to a cellulose ribbon that can reach several micrometers in length and combine with ribbons from other cells to form a robust biofilm matrix. We were able to take direct measurements in a near-native state of the cellulose sheets. Our results also reveal a novel cytoskeletal structure, which we have named the cortical belt, adjacent to the inner membrane and underlying the sites where cellulose is seen emerging from the cell. We found that this structure is not present in other cellulose-synthesizing bacterial species, Agrobacterium tumefaciens and Escherichia coli 1094, which do not produce organized cellulose ribbons. We therefore propose that the cortical belt holds the cellulose synthase complexes in a line to form higher-order cellulose structures, such as sheets and ribbons. IMPORTANCE This work’s relevance for the microbiology community is twofold. It delivers for the first time high-resolution near-native snapshots of Gluconacetobacter spp. (previously Komagataeibacter spp.) in the process of cellulose ribbon synthesis, in their native biofilm environment. It puts forward a noncharacterized cytoskeleton element associated with the side of the cell where the cellulose synthesis occurs. This represents a step forward in the understanding of the cell-guided process of crystalline cellulose synthesis, studied specifically in the Gluconacetobacter genus and still not fully understood. Additionally, our successful attempt to use cryo-focused-ion-beam milling through biofilms to image the cells in their native environment will drive the community to use this tool for the morphological characterization of other studied biofilms.