Spatiotemporal regulation of bacterial cell envelope assembly

项目总结/摘要 尽管它们的体积很小，但细菌细胞在空间和时间上精确地同步细胞过程。细胞 细菌的包膜是在细胞周期中协调组装的复杂和动态结构。 革兰氏阳性菌的细胞壁锚定表面蛋白是主要的细胞被膜组分， 通过细胞质膜分泌并通过分选酶A共价连接到细胞壁肽聚糖 （SrtA）。引人注目的是，许多表面蛋白含有特异性YSIRK/G-S信号肽，该信号肽将蛋白质靶向细胞表面。 细胞分裂时的横壁。与细胞分裂和细胞壁合成相协调，跨壁靶向 促进表面蛋白质与新合成的跨壁肽聚糖的有效结合;然而， 其机制仍不清楚。已经提出YSIRK/G-S信号肽促进局部化， 分裂隔膜处的分泌物。然而，通过在我们的模式生物中开发一种新的显微镜方法， 金黄色葡萄球菌，我们现在提供的证据表明，与流行的模型相比，靶向不 在分泌过程中发生，而是SrtA依赖性的。我们进一步发现，跨壁靶向是受调控的， 另一个重要的细胞包膜成分：LtaS介导的脂磷壁酸（LTA）合成和D- 磷壁酸的丙氨酰化。有趣的是，LTA合成和D-丙氨酰化调节不同的生物发生阶段： LTA调节SrtA介导的间隔锚定，而D-丙氨酰化调节跨壁沉积。 总的来说，这些来自我自己实验室的最新发现构成了我独立研究计划的基础 这个MIRA应用程序。我们将阐明YSIRK/G-S信号肽，LTA 合成和D-丙氨酰化在空间上调节细胞周期中的表面蛋白生物合成。成功 研究项目的完成不仅将揭示表面蛋白生物合成的新机制， 在革兰氏阳性细菌中，还揭示了LTA和D-丙氨酰化在细胞包膜组装中新功能， 提供了细菌细胞在生长过程中如何精确协调细胞包膜组装的基本见解 和细胞分裂。

Project Summary/Abstract Despite their small size, bacterial cells precisely synchronize cellular processes in space and time. The cell envelopes of bacteria are complex and dynamic structures that are coordinately assembled during the cell cycle. Cell wall anchored surface proteins of Gram-positive bacteria are major cell envelope components, which are secreted across the cytoplasmic membrane and covalently attached to cell wall peptidoglycan by sortase A (SrtA). Strikingly, many surface proteins contain a specific YSIRK/G-S signal peptide that targets proteins to the cross-wall during cell division. Coordinated with cell division and cell wall synthesis, cross-wall targeting promotes efficient incorporation of surface proteins to the newly synthesized cross-wall peptidoglycan; however, the mechanisms remain unknown. It has been proposed that the YSIRK/G-S signal peptide promotes localized secretion at the division septum. However, by developing a new microscopy method in our model organism of Staphylococcus aureus, we now provide evidence that in contrast to the prevailing model, the targeting does not occur during secretion, but rather is SrtA-dependent. We further discovered that cross-wall targeting is regulated by another important cell envelope component: LtaS-mediated lipoteichoic acid (LTA) synthesis and D- alanylation of teichoic acids. Intriguingly, LTA synthesis and D-alanylation regulate different biogenesis stages: LTA regulates SrtA-mediated septal anchoring whereas D-alanylation modulates cross-wall deposition. Collectively, these recent discoveries from my own lab form the foundation of my independent research program for this MIRA application. We will elucidate the distinct mechanisms by which the YSIRK/G-S signal peptide, LTA synthesis and D-alanylation spatially regulate surface protein biogenesis during the cell cycle. Successful completion of the research projects will not only reveal novel mechanisms underlying surface protein biogenesis in Gram-positive bacteria, but also uncover novel functions of LTA and D-alanylation in cell envelope assembly, providing fundamental insight into how bacterial cells precisely coordinate cell envelope assembly during growth and cell division.