Wang Hui, Zhang Jiayan, Liao Shiqing, Henstra Anne M, Leon Deborah, Erde Jonathan, Loo Joseph A, Ogorzalek Loo Rachel R, Zhou Z Hong, Gunsalus Robert P
Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
Department of Bioengineering, UCLA, Los Angeles, CA 90095, USA.
Sci Adv. 2024 Dec 13;10(50):eadr8596. doi: 10.1126/sciadv.adr8596.
Archaea share genomic similarities with Eukarya and cellular architectural similarities with Bacteria, though archaeal and bacterial surface layers (S-layers) differ. Using cellular cryo-electron tomography, we visualized the S-layer lattice surrounding , a methanogenic archaeon. Though more compact than known structures, 's S-layer is a flexible hexagonal lattice of dome-shaped tiles, uniformly spaced from both the overlying cell sheath and the underlying cell membrane. Subtomogram averaging resolved the S-layer hexamer tile at 6.4-angstrom resolution. By fitting an AlphaFold model into hexamer tiles in flat and curved conformations, we uncover intra- and intertile interactions that contribute to the S-layer's cylindrical and flexible architecture, along with a spacer extension for cell membrane attachment. cell's end plug structure, likely composed of S-layer isoforms, further highlights the uniqueness of this archaeal cell. These structural features offer advantages for methane release and reflect divergent evolutionary adaptations to environmental pressures during early microbial emergence.
古菌与真核生物有基因组相似性，与细菌有细胞结构相似性，尽管古菌和细菌的表层（S层）有所不同。利用细胞冷冻电子断层扫描技术，我们可视化了产甲烷古菌周围的S层晶格。尽管比已知结构更紧凑，但的S层是由圆顶形瓦片组成的灵活六边形晶格，与上层的细胞鞘和下层的细胞膜均匀间隔。亚断层平均法以6.4埃的分辨率解析了S层六聚体瓦片。通过将AlphaFold模型拟合到扁平和平曲构象的六聚体瓦片中，我们发现了有助于S层圆柱形和灵活结构的瓦片内和瓦片间相互作用，以及用于细胞膜附着的间隔延伸。细胞的端塞结构可能由S层异构体组成，进一步突出了这种古菌细胞的独特性。这些结构特征为甲烷释放提供了优势，并反映了早期微生物出现期间对环境压力的不同进化适应。
