Science for Life Laboratory and Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
Science for Life Laboratory and Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
mBio. 2021 May 4;12(3):e03564-20. doi: 10.1128/mBio.03564-20.
The highly conserved chaperonin GroESL performs a crucial role in protein folding; however, the essential cellular pathways that rely on this chaperone are underexplored. Loss of GroESL leads to severe septation defects in diverse bacteria, suggesting the folding function of GroESL may be integrated with the bacterial cell cycle at the point of cell division. Here, we describe new connections between GroESL and the bacterial cell cycle using the model organism Using a proteomics approach, we identify candidate GroESL client proteins that become insoluble or are degraded specifically when GroESL folding is insufficient, revealing several essential proteins that participate in cell division and peptidoglycan biosynthesis. We demonstrate that other cell cycle events, such as DNA replication and chromosome segregation, are able to continue when GroESL folding is insufficient. We further find that deficiency of two FtsZ-interacting proteins, the bacterial actin homologue FtsA and the constriction regulator FzlA, mediate the GroESL-dependent block in cell division. Our data show that sufficient GroESL is required to maintain normal dynamics of the FtsZ scaffold and divisome functionality in In addition to supporting divisome function, we show that GroESL is required to maintain the flow of peptidoglycan precursors into the growing cell wall. Linking a chaperone to cell division may be a conserved way to coordinate environmental and internal cues that signal when it is safe to divide. All organisms depend on mechanisms that protect proteins from misfolding and aggregation. GroESL is a highly conserved molecular chaperone that functions to prevent protein aggregation in organisms ranging from bacteria to humans. Despite detailed biochemical understanding of GroESL function, the pathways that strictly depend on this chaperone remain poorly defined in most species. This study provides new insights into how GroESL is linked to the bacterial cell division machinery, a crucial target of current and future antimicrobial agents. We identify a functional interaction between GroESL and the cell division proteins FzlA and FtsA, which modulate Z-ring function. FtsA is a conserved bacterial actin homologue, suggesting that as in eukaryotes, some bacteria exhibit a connection between cytoskeletal actin proteins and chaperonins. Our work further defines how GroESL is integrated with cell wall synthesis and illustrates how highly conserved folding machines ensure the functioning of fundamental cellular processes during stress.
GroESL 是高度保守的分子伴侣，在蛋白质折叠中发挥着关键作用；然而，依赖这种伴侣的重要细胞途径仍未得到充分探索。GroESL 的缺失会导致多种细菌严重的分隔缺陷，这表明 GroESL 的折叠功能可能在细胞分裂时与细菌细胞周期整合在一起。在这里，我们使用模式生物 通过蛋白质组学方法，我们鉴定了候选的 GroESL 客户蛋白，当 GroESL 折叠不足时，这些蛋白会变得不溶或降解，这揭示了几个参与细胞分裂和肽聚糖生物合成的必需蛋白。我们证明，当 GroESL 折叠不足时，其他细胞周期事件，如 DNA 复制和染色体分离，仍能继续进行。我们进一步发现，两种与 FtsZ 相互作用的蛋白质，细菌肌动蛋白同源物 FtsA 和收缩调节因子 FzlA 的缺乏，介导了 GroESL 依赖的细胞分裂阻断。我们的数据表明，足够的 GroESL 是维持 在支持分裂体功能的同时，我们还表明，GroESL 对于维持 FtsZ 支架和分裂体功能的正常动力学是必需的。除了支持分裂体功能外，我们还表明，GroESL 对于将肽聚糖前体流入正在生长的细胞壁中是必需的。将伴侣与细胞分裂联系起来可能是一种协调环境和内部信号的保守方式，这些信号表明何时安全分裂。所有生物体都依赖于保护蛋白质免受错误折叠和聚集的机制。GroESL 是一种高度保守的分子伴侣，在从细菌到人类的生物体中，它的功能是防止蛋白质聚集。尽管对 GroESL 功能的详细生化理解已经很清楚，但在大多数物种中，严格依赖这种伴侣的途径仍然定义不明确。这项研究提供了新的见解，说明 GroESL 如何与细菌细胞分裂机制联系在一起，这是当前和未来抗菌药物的关键靶点。我们鉴定了 GroESL 与细胞分裂蛋白 FzlA 和 FtsA 之间的功能相互作用，这些蛋白调节 Z 环的功能。FtsA 是一种保守的细菌肌动蛋白同源物，这表明，与真核生物一样，一些细菌表现出细胞骨架肌动蛋白蛋白与伴侣之间的联系。我们的工作进一步定义了 GroESL 如何与细胞壁合成整合在一起，并说明了高度保守的折叠机器如何在压力下确保基本细胞过程的正常运转。
