Ribosome Abundance Control in Prokaryotes

Cell growth is an essential phenotype of any unicellular organism and it crucially depends on precise control of protein synthesis. We construct a model of the feedback mechanisms that regulate abundance of ribosomes in E. coli, a prototypical prokaryotic organism. Since ribosomes are needed to produce more ribosomes, the model includes a positive feedback loop central to the control of cell growth. Our analysis of the model shows that there can be only two coexisting equilibrium states across all 23 parameters. This precludes the existence of hysteresis, suggesting that the ribosome abundance changes continuously with parameters. These states are related by a transcritical bifurcation, and we provide an analytic formula for parameters that admit either state.

Automated summary

Cell growth is crucial for the survival of unicellular organisms, and it relies heavily on precise control of protein synthesis. This study constructs a model to investigate the feedback mechanisms regulating ribosome abundance in E. coli, a prototypical prokaryotic organism. The findings reveal the existence of two coexisting equilibrium states, with ribosome abundance continuously changing with parameters.