Cellular resource allocation strategies for cell size and shape control in bacteria

Abstract

Bacteria are highly adaptive microorganisms that thrive in a wide range of growth conditions via changes in cell morphologies and macromolecular composition. How bacterial morphologies are regulated in diverse environmental conditions is a long‐standing question. Regulation of cell size and shape implies control mechanisms that couple the growth and division of bacteria to their cellular environment and macromolecular composition. In the past decade, simple quantitative laws have emerged that connect cell growth to proteomic composition and the nutrient availability. However, the relationships between cell size, shape, and growth physiology remain challenging to disentangle and unifying models are lacking. In this review, we focus on regulatory models of cell size control that reveal the connections between bacterial cell morphology and growth physiology. In particular, we discuss how changes in nutrient conditions and translational perturbations regulate the cell size, growth rate, and proteome composition. Integrating quantitative models with experimental data, we identify the physiological principles of bacterial size regulation, and discuss the optimization strategies of cellular resource allocation for size control.

Modulation of prey size reveals adaptability and robustness in the cell cycle of an intracellular predator

“…Our findings also provide clues on what prey molecules B. bacteriovorus preferentially feeds upon. Because E. coli cells growing in rich medium (e.g., LB) contain relatively more (ribosomal) RNA and proteins than in poor medium (e.g., M9) [25][26][27]32], RNAs and/or proteins might constitute the primary resources fueling predator growth. With the impressive number (~150) of putative proteases/peptidases encoded in its genome [33] (i) the size of the prey, which determines how many daughter cells are produced, and therefore how much the predator cell needs to grow and how many copies of its chromosome must be synthesized and segregated (Fig 5A ), and (ii) the nutritive quality of the prey cell, which impacts how fast the predator elongates (Fig 5B).…”

“…To this end, we grew E. coli in different media, either LB (a rich and undefined medium, as done in Fig 1-3) or M9 supplemented with glucose and casamino acids (a relatively poor and defined medium) prior to infection by B. bacteriovorus. Indeed, previous work demonstrated that in these distinct growth conditions, the cellular dry mass of E. coli does not change [23,24] but the cellular resource allocation (i.e., the macromolecular composition of the cytoplasm) varies [25][26][27]. For instance, E. coli cells grown in LB contain relatively more proteins than cells grown in M9.…”

Antibiotic Resistance via Bacterial Cell Shape-Shifting

“…The data in Fig. 4B can now be interpreted using the framework of cellular resource allocation ( 34 ). Upon treatment with chloramphenicol, cells upregulate ribosome synthesis to compensate for ribosome inhibition by chloramphenicol ( 32 ).…”

Super-exponential growth and stochastic size dynamics in rod-like bacteria

“…Recent advances in single-cell imaging and microfluidics have resulted in large amounts of high-quality datasets on the size and shapes of single bacterial cells as they grow and divide [2][3][4][5][6][7]. These data have revealed many fundamental models and principles underlying single-cell physiology, including the mechanisms of cell size homeostasis and division control [4,[8][9][10][11][12][13], cell size control and growth physiology [12,[14][15][16], cell shape control [11,[17][18][19] and adaptation to environmental changes [20][21][22][23]. While extensive work has been done to characterize cell size regulation and division control at the inter-generational level [12], much less is understood about the dynamics of cell growth within an individual cell cycle.…”