Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK.
Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK.
Nat Commun. 2024 Apr 18;15(1):3355. doi: 10.1038/s41467-024-47529-5.
Surface layers (S-layers) are proteinaceous, two-dimensional paracrystalline arrays that constitute a major component of the cell envelope in many prokaryotic species. In this study, we investigated S-layer biogenesis in the bacterial model organism Caulobacter crescentus. Fluorescence microscopy revealed localised incorporation of new S-layer at the poles and mid-cell, consistent with regions of cell growth in the cell cycle. Light microscopy and electron cryotomography investigations of drug-treated bacteria revealed that localised S-layer insertion is retained when cell division is inhibited, but is disrupted upon dysregulation of MreB or lipopolysaccharide. We further uncovered that S-layer biogenesis follows new peptidoglycan synthesis and localises to regions of high cell wall turnover. Finally, correlated cryo-light microscopy and electron cryotomographic analysis of regions of S-layer insertion showed the presence of discontinuities in the hexagonal S-layer lattice, contrasting with other S-layers completed by defined symmetric defects. Our findings present insights into how C. crescentus cells form an ordered S-layer on their surface in coordination with the biogenesis of other cell envelope components.
表面层(S-层)是由蛋白质组成的二维准晶阵列,构成许多原核生物物种细胞包膜的主要成分。在这项研究中,我们研究了细菌模式生物新月柄杆菌中 S-层的生物发生。荧光显微镜显示,新的 S-层在细菌的极区和细胞中部局部掺入,与细胞周期中的细胞生长区域一致。对药物处理的细菌进行的光学显微镜和电子晶体断层扫描研究表明,当细胞分裂受到抑制时,局部 S-层插入仍然保留,但当 MreB 或脂多糖失调时,S-层插入会被打乱。我们还发现,S-层的生物发生遵循新的肽聚糖合成,并定位于细胞壁周转率高的区域。最后,对 S-层插入区域的共聚焦冷冻光显微镜和电子晶体断层扫描分析表明,在六边形 S-层晶格中存在不连续性,与其他通过明确的对称缺陷完成的 S-层形成对比。我们的研究结果提供了关于新月柄杆菌细胞如何与其他细胞包膜成分的生物发生协调,在其表面形成有序 S-层的见解。