Pavlou Antrea, Cinquemani Eugenio, Pinel Corinne, Giordano Nils, Mathilde Van Melle-Gateau, Mihalcescu Irina, Geiselmann Johannes, de Jong Hidde
Univ. Grenoble Alpes, Inria, Grenoble, France.
Univ. Grenoble Alpes, CNRS, LIPhy, Grenoble, France.
Nat Commun. 2025 Jan 2;16(1):285. doi: 10.1038/s41467-024-55394-5.
Ribosomes are responsible for the synthesis of proteins, the major component of cellular biomass. Classical experiments have established a linear relationship between the fraction of resources invested in ribosomal proteins and the rate of balanced growth of a microbial population. Very little is known, however, about how the investment in ribosomes varies over individual cells in a population. We therefore extended the study of ribosomal resource allocation from populations to single cells, using a combination of time-lapse fluorescence microscopy and statistical inference. We found a large variability of ribosome concentrations and growth rates in conditions of balanced growth of the model bacterium Escherichia coli in a given medium, which cannot be accounted for by the population-level growth law. A large variability in the allocation of resources to ribosomes was also found during the transition of the bacteria from a poor to a rich growth medium. While some cells immediately adapt their ribosome synthesis rate to the new environment, others do so only gradually. Our results thus reveal a range of strategies for investing resources in the molecular machines at the heart of cellular self-replication. This raises the fundamental question whether the observed variability is an intrinsic consequence of the stochastic nature of the underlying biochemical processes or whether it improves the fitness of Escherichia coli in its natural environment.
核糖体负责蛋白质的合成，而蛋白质是细胞生物质的主要成分。经典实验已经确立了投入核糖体蛋白质的资源比例与微生物群体平衡生长速率之间的线性关系。然而，对于群体中单个细胞的核糖体投入如何变化，我们知之甚少。因此，我们结合延时荧光显微镜和统计推断，将核糖体资源分配的研究从群体扩展到了单个细胞。我们发现，在给定培养基中，模式细菌大肠杆菌平衡生长的条件下，核糖体浓度和生长速率存在很大差异，而群体水平的生长规律无法解释这种差异。在细菌从贫养生长培养基过渡到富养生长培养基的过程中，我们还发现核糖体资源分配存在很大差异。一些细胞会立即将其核糖体合成速率调整到新环境，而另一些细胞则只是逐渐调整。因此，我们的研究结果揭示了一系列在细胞自我复制核心的分子机器上投入资源的策略。这就引出了一个基本问题，即观察到的差异是潜在生化过程随机性的内在结果，还是它提高了大肠杆菌在自然环境中的适应性。
