Subpopulations of sensorless bacteria drive fitness in fluctuating environments
| Autor: | Athos Fiori, Erik van Nimwegen, Thomas Julou, Ludovit P. Zweifel, Diana Blank |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
Luminescence Microfluidics lac operon Lactose Disaccharides Biochemistry 0302 clinical medicine Nucleic Acids Gene expression Gene Regulatory Networks Inducer Cell Cycle and Cell Division Biology (General) Regulation of gene expression education.field_of_study Natural selection Organic Compounds Physics Electromagnetic Radiation Escherichia coli Proteins General Neuroscience Monosaccharides Cell biology Chemistry Phenotype Lac Operon Cell Processes Physical Sciences Engineering and Technology Fluidics General Agricultural and Biological Sciences Research Article QH301-705.5 Lag Population Carbohydrates Environment Biology Green Fluorescent Protein Fluorescence General Biochemistry Genetics and Molecular Biology Bacterial genetics 03 medical and health sciences Population Metrics Genetics Escherichia coli Operons Population Growth education Gene Population Biology Bacteria General Immunology and Microbiology Organic Chemistry Chemical Compounds Biology and Life Sciences Proteins DNA Cell Biology Gene Expression Regulation Bacterial Luminescent Proteins Noise Glucose 030104 developmental biology Gene-Environment Interaction Genetic Fitness 030217 neurology & neurosurgery |
| Zdroj: | PLoS Biology PLoS Biology, Vol 18, Iss 12, p e3000952 (2020) |
| DOI: | 10.5451/unibas-ep79966 |
| Popis: | Populations of bacteria often undergo a lag in growth when switching conditions. Because growth lags can be large compared to typical doubling times, variations in growth lag are an important but often overlooked component of bacterial fitness in fluctuating environments. We here explore how growth lag variation is determined for the archetypical switch from glucose to lactose as a carbon source in Escherichia coli. First, we show that single-cell lags are bimodally distributed and controlled by a single-molecule trigger. That is, gene expression noise causes the population before the switch to divide into subpopulations with zero and nonzero lac operon expression. While “sensorless” cells with zero preexisting lac expression at the switch have long lags because they are unable to sense the lactose signal, any nonzero lac operon expression suffices to ensure a short lag. Second, we show that the growth lag at the population level depends crucially on the fraction of sensorless cells and that this fraction in turn depends sensitively on the growth condition before the switch. Consequently, even small changes in basal expression can significantly affect the fraction of sensorless cells, thereby population lags and fitness under switching conditions, and may thus be subject to significant natural selection. Indeed, we show that condition-dependent population lags vary across wild E. coli isolates. Since many sensory genes are naturally low expressed in conditions where their inducer is not present, bimodal responses due to subpopulations of sensorless cells may be a general mechanism inducing phenotypic heterogeneity and controlling population lags in switching environments. This mechanism also illustrates how gene expression noise can turn even a simple sensory gene circuit into a bet hedging module and underlines the profound role of gene expression noise in regulatory responses. Is ignorance bliss for some bacterial cells? Single-cell analysis of the archetypical switch from glucose to lactose as a carbon source in E. coli shows that bacteria can exhibit stochastic bimodal responses to external stimuli because the corresponding sensory circuit is so lowly expressed that some cells are effectively blind to the stimulus. |
| Databáze: | OpenAIRE |
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