Bacterial osmoadaptation: coordination of osmoregulatory systems and their roles in cell growth

渗透压的变化导致水流过包裹活细胞的细胞膜。这样的水通量会扰乱细胞的结构和功能。细胞通过调整有机渗透物（氨基酸、糖等）的含量来做出反应。这种“渗透调节”控制水流，以确保细胞保持适当的水分，稳定其内部机制，并支持其持续生长。已经描述了调节细菌渗透物含量的渗透调节机制。现在我们的目标是了解大肠杆菌的渗透调节系统是如何协调的。我们将检验以下假设。首先，ProQ蛋白是一种RNA伴侣蛋白，它调节编码渗透调节蛋白的基因，包括ProP和ProU。其次，ProP与其他膜基渗透调节蛋白聚集在大肠杆菌细胞的末端，呈棒状。这种由细胞膜和“细胞骨架”组分之间的特定相互作用引起的蛋白质聚集是有效渗透调节和细胞生长所必需的。

Osmotic pressure changes cause water to flow across the membranes that encase living cells. Such water fluxes can perturb cell structures and functions. Cells respond by adjusting their content of substances called organic osmolytes (amino acids, sugars etc). This "osmoregulation" controls water flow to ensure that cells remain properly hydrated, to stabilize their internal machinery, and to support their continuing growth. The osmoregulatory machinery that modulates bacterial osmolyte content has been described. Now we aim to learn how the osmoregulatory systems of bacterium Escherichia coli are coordinated. We will test the following hypotheses. First, the ProQ protein is an RNA chaperone that regulates the genes encoding osmoregulatory proteins, including ProP and ProU. Second, ProP clusters with other membrane-based osmoregulatory proteins at the ends of E. coli cells, which are rod-shaped. This protein clustering, resulting from specific interactions among cell membrane and "cell skeleton" components, is necessary for effective osmoregulation and cell growth.