Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel.
Curr Biol. 2023 Nov 20;33(22):4880-4892.e14. doi: 10.1016/j.cub.2023.09.064. Epub 2023 Oct 24.
Bacteria undergo cycles of growth and starvation to which they must adapt swiftly. One important strategy for adjusting growth rates relies on ribosomal levels. Although high ribosomal levels are required for fast growth, their dynamics during starvation remain unclear. Here, we analyzed ribosomal RNA (rRNA) content of individual Salmonella cells by using fluorescence in situ hybridization (rRNA-FISH) and measured a dramatic decrease in rRNA numbers only in a subpopulation during nutrient limitation, resulting in a bimodal distribution of cells with high and low rRNA content. During nutritional upshifts, the two subpopulations were associated with distinct phenotypes. Using a transposon screen coupled with rRNA-FISH, we identified two mutants, DksA and RNase I, acting on rRNA transcription shutdown and degradation, which abolished the formation of the subpopulation with low rRNA content. Our work identifies a bacterial mechanism for regulation of ribosomal bimodality that may be beneficial for population survival during starvation.
细菌经历生长和饥饿的循环，它们必须迅速适应。一种调整生长速度的重要策略依赖于核糖体的水平。虽然快速生长需要高核糖体水平，但它们在饥饿期间的动态仍然不清楚。在这里，我们通过荧光原位杂交（rRNA-FISH）分析了单个沙门氏菌细胞的核糖体 RNA（rRNA）含量，并仅在营养限制期间的亚群中观察到 rRNA 数量的显著减少，导致 rRNA 含量高和低的细胞呈双峰分布。在营养上升期间，这两个亚群与不同的表型相关。通过转座子筛选结合 rRNA-FISH，我们鉴定了两个突变体，DksA 和 RNase I，它们作用于 rRNA 转录关闭和降解，从而消除了低 rRNA 含量亚群的形成。我们的工作确定了细菌调节核糖体双峰性的机制，这可能有利于细菌在饥饿期间的种群生存。
