Abstract
Despite abundant measurements of bacterial growth rate, cell size, and protein content, we lack a rigorous understanding of what sets the scale of these quantities and when protein abundances should (or should not) depend on growth rate. Here, we estimate the basic requirements and physical constraints on steady-state growth by considering key processes in cellular physiology across a collection of Escherichia coli proteomic data covering ≈4,000 proteins and 36 growth rates. Our analysis suggests that cells are predominantly tuned for the task of cell doubling across a continuum of growth rates; specific processes do not limit growth rate or dictate cell size. We present a model of proteomic regulation as a function of nutrient supply that reconciles observed interdependences between protein synthesis, cell size, and growth rate and propose that a theoretical inability to parallelize ribosomal synthesis places a firm limit on the achievable growth rate. A record of this paper’s transparent peer review process is included in the supplemental information.
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•Key biological processes are considered as potential growth-rate-limiting steps•A near-comprehensive dataset of the E. coli proteome across growth rates is presented•Order-of-magnitude estimates suggest little inefficiency across key processes•Translation emerges as a rate-governing process and we explore constraints on growth rate
Identifying factors that determine growth rate has long been central to the study of bacterial physiology. Belliveau and Chure et al. present order-of-magnitude estimates of the proteomic requirements for various biological processes in Escherichia coli across growth rates and compare them to experimental measurements. This reveals translation to be key in defining the growth rate, while other processes are precisely tuned with little excess. The influence of physiological parameters on growth rate is explored using a simple mathematical model.