Bacterial growth: global effects on gene expression, growth feedback and proteome partition

• Genes and genetic circuits exhibit growth-rate dependence.
• Growth rate dependence reflects coupling of gene expression and physiological state of the cell.
• Several types of growth rate dependencies are distinguished.
• Growth rate dependence can mediate feedback if a gene product affects growth.
• Simple growth relations arise from signals coordinating gene expression with metabolic fluxes.

The function of endogenous as well as synthetic genetic circuits is generically coupled to the physiological state of the cell. For exponentially growing bacteria, a key characteristic of the state of the cell is the growth rate and thus gene expression is often growth-rate dependent. Here we review recent results on growth-rate dependent gene expression. We distinguish different types of growth-rate dependencies by the mechanisms of regulation involved and the presence or absence of an effect of the gene product on growth. The latter can lead to growth feedback, feedback mediated by changes of the global state of the cell. Moreover, we discuss how growth rate dependence can be used as a guide to study the molecular implementation of physiological regulation.

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