Size Laws and Division Ring Dynamics in Filamentous Escherichia coli cells

Abstract

Our understanding of bacterial cell size control is based mainly on stress-free growth conditions in the laboratory [1-10]. In the real world, however, bacteria are routinely faced with stresses that produce long filamentous cell morphologies [11-28]. Escherichia coli is observed to filament in response to DNA damage [22-25], antibiotic treatment [11-14, 28], host immune systems [15, 16], temperature [17], starvation [20], and more [18, 19, 21], conditions which are relevant to clinical settings and food preservation [26]. This shape plasticity is considered a survival strategy [27]. Size control in this regime remains largely unexplored. Here we report that E. coli cells use a dynamic size ruler to determine division locations combined with an adder-like mechanism to trigger divisions. As filamentous cells increase in size due to growth, or decrease in size due to divisions, its multiple Fts division rings abruptly reorganize to remain one characteristic cell length away from the cell pole and two such length units away from each other. These rules can be explained by spatiotemporal oscillations of Min proteins. Upon removal of filamentation stress, the cells undergo a sequence of division events, randomly at one of the possible division sites, on average after the time required to grow one characteristic cell size. These results indicate that E. coli cells continuously keep track of absolute length to control size, suggest a wider relevance for the adder principle beyond the control of normally sized cells, and provide a new perspective on the function of the Fts and Min systems.

Analysis of Cell Size Homeostasis at the Single-Cell and Population Level

“…The numerical results for the backward distribution ψ bw shown in Figure 1B are qualitatively very similar to the tree distribution obtained via Equation (15) and also to the lineage distribution computed by solving Equation (4).…”

“…We hence expect our conclusions to hold also for developed models of cell size control. We found that these differences are particularly sensitive to division errors, which can be extremely heterogeneous when cells respond to stress [4]. Conversely, we found that cells dividing at smaller sizes are over-represented in the population tree when division size is highly variable.…”

“…A key question is therefore why cells grow to a certain size, how they maintain their sizes within a narrow distribution and what are the dominant sources of size variations. Recent experiments investigate this issue by taking snapshots of populations [1], trapping single cells [2] or recording movies of growing populations [3,4]. Currently, we lack the tools with which to compare these different data.…”

A cell length‐dependent transition in MinD‐dynamics promotes a switch in division‐site placement and preservation of proliferating elongated Vibrio parahaemolyticus swarmer cells

“…Indeed, recently it was shown that in artificially generated filamentous E. coli cells the Z‐ring reorganize to form one cell length (the length of a non‐elongated cell) away from the cell pole and regularly at a distance of two length‐units away from each other along the cell length. Interestingly, these localization patterns of the Z‐ring could be attributed to the localization dynamics of the Min‐system (Wehrens et al, ).…”

In long bacterial cells, the Min system can act off‐center

“…Wehrens and Ershove et al recently published highly complementary findings in E. coli cells that were elongated due to stress (Wehrens et al, ). In these growing filamentous cells, multiple Fts rings were evenly distributed in response to the multi‐nodal dynamics of the Min system.…”