Delerue Thomas, Chareyre Sylvia, Anantharaman Vivek, Gilmore Michael C, Popham David L, Cava Felipe, Aravind L, Ramamurthi Kumaran S
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA.
bioRxiv. 2023 Oct 6:2023.10.06.561273. doi: 10.1101/2023.10.06.561273.
spores are produced inside the cytosol of a mother cell. Spore surface assembly requires the SpoVK protein in the mother cell, but its function is unknown. Here, we report that SpoVK is a dedicated chaperone from a distinct higher-order clade of AAA+ ATPases that activates the peptidoglycan glycosyltransferase MurG during sporulation, even though MurG does not normally require activation by a chaperone during vegetative growth. MurG redeploys to the spore surface during sporulation, where we show that the local pH is reduced and propose that this change in cytosolic nanoenvironment necessitates a specific chaperone for proper MurG function. Further, we show that SpoVK participates in a developmental checkpoint in which improper spore surface assembly inactivates SpoVK, which leads to sporulation arrest. The AAA+ ATPase clade containing SpoVK includes other dedicated chaperones involved in secretion, cell-envelope biosynthesis, and carbohydrate metabolism, suggesting that such fine-tuning might be a widespread feature of different subcellular nanoenvironments.
孢子在母细胞的胞质溶胶中产生。孢子表面组装需要母细胞中的SpoVK蛋白，但其功能尚不清楚。在这里，我们报告SpoVK是一种来自AAA+ATP酶独特高阶进化枝的专用伴侣蛋白，在孢子形成过程中激活肽聚糖糖基转移酶MurG，尽管MurG在营养生长期间通常不需要伴侣蛋白的激活。MurG在孢子形成过程中重新部署到孢子表面，我们发现那里的局部pH值降低，并提出这种胞质纳米环境的变化需要一种特定的伴侣蛋白来实现MurG的正常功能。此外，我们表明SpoVK参与了一个发育检查点，其中孢子表面组装不当会使SpoVK失活，从而导致孢子形成停滞。包含SpoVK的AAA+ATP酶进化枝包括其他参与分泌、细胞包膜生物合成和碳水化合物代谢的专用伴侣蛋白，这表明这种微调可能是不同亚细胞纳米环境的一个普遍特征。
