Laboratory of Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892.
Computational Biology Branch, Division of Intramural Research, National Library of Medicine, NIH Bethesda, MD 20894.
Proc Natl Acad Sci U S A. 2024 Oct 22;121(43):e2414737121. doi: 10.1073/pnas.2414737121. Epub 2024 Oct 15.
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 sporulation-specific, forespore-localized putative chaperone from a distinct higher-order clade of AAA+ ATPases that promotes the peptidoglycan glycosyltransferase activity of MurG during sporulation, even though MurG does not normally require activation during vegetative growth. MurG redeploys to the forespore surface during sporulation, where we show that the local pH is reduced and propose that this change in cytosolic nanoenvironment abrogates MurG function. Further, we show that SpoVK participates in a developmental checkpoint in which improper spore surface assembly mis-localizes SpoVK, which leads to sporulation arrest. The AAA+ ATPase clade containing SpoVK includes specialized chaperones involved in secretion, cell envelope biosynthesis, and carbohydrate metabolism, suggesting that such fine-tuning might be a widespread feature of different subcellular nanoenvironments.
孢子是在母细胞的细胞质内产生的。孢子表面的组装需要母细胞中的 SpoVK 蛋白，但它的功能尚不清楚。在这里，我们报告说，SpoVK 是一种来自 AAA+ATP 酶的不同高级分类群的孢子特异性、前孢子定位的假定伴侣蛋白，它在孢子形成过程中促进 MurG 的肽聚糖糖基转移酶活性，尽管 MurG 在营养生长期间通常不需要激活。MurG 在孢子形成过程中重新定位于前孢子表面，我们表明局部 pH 值降低，并提出这种细胞质纳米环境的变化会削弱 MurG 的功能。此外，我们还表明，SpoVK 参与了一个发育检查点，其中不正确的孢子表面组装会使 SpoVK 发生错误定位，从而导致孢子形成停滞。包含 SpoVK 的 AAA+ATP 酶类群包括参与分泌、细胞包膜生物合成和碳水化合物代谢的专门伴侣蛋白，这表明这种精细调控可能是不同亚细胞纳米环境的普遍特征。
