scholarly journals Universal surface-to-volume scaling and aspect ratio homeostasis in rod-shaped bacteria

2019 ◽  
Author(s):  
Nikola Ojkic ◽  
Diana Serbanescu ◽  
Shiladitya Banerjee
Keyword(s):  
Aspect Ratio ◽  
Cell Size ◽  
Bacterial Cell ◽  
Environmental Changes ◽  
Morphological Changes ◽  
Size Control ◽  
Growth Conditions ◽  
Quantitative Agreement ◽  
Quantitative Model ◽  
Bacterial Cells

AbstractRod-shaped bacterial cells can readily adapt their lengths and widths in response to environmental changes. While many recent studies have focused on the mechanisms underlying bacterial cell size control, it remains largely unknown how the coupling between cell length and width results in robust control of rod-like bacterial shapes. In this study we uncover a universal surface-to-volume scaling relation in Escherichia coli and other rod-shaped bacteria, resulting from the preservation of cell aspect ratio. To explain the mechanistic origin of aspect-ratio control, we propose a quantitative model for the coupling between bacterial cell elongation and the accumulation of an essential division protein, FtsZ. This model reveals a mechanism for why bacterial aspect ratio is independent of cell size and growth conditions, and predicts cell morphological changes in response to nutrient perturbations, antibiotics, MreB or FtsZ depletion, in quantitative agreement with experimental data.

scholarly journals Surface-to-volume scaling and aspect ratio preservation in rod-shaped bacteria

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Nikola Ojkic ◽  
Diana Serbanescu ◽  
Shiladitya Banerjee
Keyword(s):  
Aspect Ratio ◽  
Cell Size ◽  
Bacterial Cell ◽  
Environmental Changes ◽  
Morphological Changes ◽  
Size Control ◽  
Growth Conditions ◽  
Quantitative Agreement ◽  
Quantitative Model ◽  
Bacterial Cells

Rod-shaped bacterial cells can readily adapt their lengths and widths in response to environmental changes. While many recent studies have focused on the mechanisms underlying bacterial cell size control, it remains largely unknown how the coupling between cell length and width results in robust control of rod-like bacterial shapes. In this study we uncover a conserved surface-to-volume scaling relation in Escherichia coli and other rod-shaped bacteria, resulting from the preservation of cell aspect ratio. To explain the mechanistic origin of aspect-ratio control, we propose a quantitative model for the coupling between bacterial cell elongation and the accumulation of an essential division protein, FtsZ. This model reveals a mechanism for why bacterial aspect ratio is independent of cell size and growth conditions, and predicts cell morphological changes in response to nutrient perturbations, antibiotics, MreB or FtsZ depletion, in quantitative agreement with experimental data.

scholarly journals The size-wise nucleus: nuclear volume control in eukaryotes

2007 ◽  
Vol 179 (4) ◽  
pp. 583-584 ◽  
Author(s):  
Michael D. Huber ◽  
Larry Gerace
Keyword(s):  
Fission Yeast ◽  
Cell Size ◽  
Size Control ◽  
Growth Conditions ◽  
Nuclear Size ◽  
Yeast Cells ◽  
Volume Control ◽  
Wide Range ◽  
The Relationship

Eukaryotic cells have an “awareness” of their volume and organellar volumes, and maintain a nuclear size that is proportional to the total cell size. New studies in budding and fission yeast have examined the relationship between cell and nuclear volumes. It was found that the size of the nucleus remains proportional to cell size in a wide range of genetic backgrounds and growth conditions that alter cell volume and DNA content. Moreover, in multinucleated fission yeast cells, Neumann and Nurse (see p. 593 of this issue) found that the sizes of individual nuclei are controlled by the relative amount of cytoplasm surrounding each nucleus. These results highlight a role of the cytoplasm in nuclear size control.

scholarly journals Initiation of chromosome replication controls both division and replication cycles in E. coli through a double-adder mechanism

2019 ◽  
Author(s):  
Guillaume Witz ◽  
Erik van Nimwegen ◽  
Thomas Julou
Keyword(s):  
Cell Cycle ◽  
Cell Size ◽  
Cell Cycle Control ◽  
Size Control ◽  
Time Lapse ◽  
Growth Conditions ◽  
Replication Initiation ◽  
Stochastic Simulations ◽  
E Coli ◽  
Wide Range

AbstractLiving cells proliferate by completing and coordinating two essential cycles, a division cycle that controls cell size, and a DNA replication cycle that controls the number of chromosomal copies in the cell. Despite lacking dedicated cell cycle control regulators such as cyclins in eukaryotes, bacteria such as E. coli manage to tightly coordinate those two cycles across a wide range of growth conditions, including situations where multiple nested rounds of replication progress simultaneously. Various cell cycle models have been proposed to explain this feat, but it has been impossible to validate them so far due to a lack of experimental tools for systematically testing their different predictions. Recently new insights have been gained on the division cycle through the study of the structure of fluctuations in growth, size, and division in individual cells. In particular, it was found that cell size appears to be controlled by an adder mechanism, i.e. the added volume between divisions is held approximately constant and fluctuates independently of growth rate and cell size at birth. However, how replication initiation is regulated and coupled to cell size control remains unclear, mainly due to scarcity of experimental measurements on replication initiation at the single-cell level. Here, we used time-lapse microscopy in combination with microfluidics to directly measure growth, division and replication in thousands of single E. coli cells growing in both slow and fast growth conditions. In order to compare different phenomenological models of the cell cycle, we introduce a statistical framework which assess their ability to capture the correlation structure observed in the experimental data. Using this in combination with stochastic simulations, our data indicate that, instead of thinking of the cell cycle as running from birth to division, the cell cycle is controlled by two adder mechanisms starting at the initiation of replication: the added volume since the last initiation event controls the timing of both the next division event and the next replication initiation event. Interestingly the double-adder mechanism identified in this study has recently been found to explain the more complex cell cycle of mycobacteria, suggesting shared control strategies across species.

scholarly journals Dot6 is a major regulator of cell size and a transcriptional activator of ribosome biogenesis in the opportunistic yeast Candida albicans

2018 ◽  
Author(s):  
Julien Chaillot ◽  
Jaideep Malick ◽  
Adnane Sellam
Keyword(s):  
Candida Albicans ◽  
Cell Size ◽  
Ribosome Biogenesis ◽  
Size Control ◽  
Transcriptional Activator ◽  
Growth Conditions ◽  
Mitotic Division ◽  
Negative Regulator ◽  
Restriction Point ◽  
Tor Pathway

AbstractIn most species, size homeostasis appears to be exerted in late G1 phase as cells commit to division, called Start in yeast and the Restriction Point in metazoans. This size threshold couples cell growth to division and thereby establishes long-term size homeostasis. Our former investigations have shown that hundreds of genes markedly altered cell size under homeostatic growth conditions in the opportunistic yeast Candida albicans, but surprisingly only few of these overlapped with size control genes in the budding yeast Saccharomyces cerevisiae. Here, we investigated one of the divergent potent size regulators in C. albicans, the Myb-like HTH transcription factor Dot6. Our data demonstrated that Dot6 is a negative regulator of Start and also acts as a transcriptional activator of ribosome biogenesis (Ribi) genes. Genetic epistasis uncovered that Dot6 interacted with the master transcriptional regulator of the G1 machinery, SBF complex, but not with the Ribi and cell size regulators Sch9, Sfp1 and p38/Hog1. Dot6 was required for carbon-source modulation of cell size and it is regulated at the level of nuclear localization by TOR pathway. Our findings support a model where Dot6 acts as a hub that integrate directly growth cues via the TOR pathway to control the commitment to mitotic division at G1.

scholarly journals Nutrient-dependent trade-offs between ribosomes and division protein synthesis control bacterial cell size and growth

2020 ◽  
Author(s):  
Diana Serbanescu ◽  
Nikola Ojkic ◽  
Shiladitya Banerjee
Keyword(s):  
Experimental Data ◽  
Protein Synthesis ◽  
Cell Size ◽  
Bacterial Cell ◽  
Cell Model ◽  
Morphological Changes ◽  
Growth Dynamics ◽  
Cellular Growth ◽  
Trade Off ◽  
Trade Offs

SUMMARYCell size control emerges from a regulated balance between the rates of cell growth and division. In bacteria, simple quantitative laws connect cellular growth rate to ribosome abundance. However, it remains poorly understood how translation regulates bacterial cell size and shapes under growth perturbations. Here we develop a whole-cell model for growth dynamics in rod-shaped bacteria that links ribosomal abundance with cell geometry, division control, and the extracellular environment. Our study reveals that cell size maintenance under nutrient perturbations requires a balanced trade-off between ribosomes and division protein synthesis. Deviations from this trade-off relationship are predicted under translational perturbations, leading to distinct modes of cell morphological changes, in agreement with single-cell experimental data on Escherichia coli. Furthermore, by calibrating our model with experimental data, we predict how combinations of nutrient-, translational- and shape perturbations can be chosen to optimize bacterial growth fitness and antibiotic resistance.

scholarly journals Coordination of gene expression with cell size enables Escherichia coli to efficiently maintain motility across conditions

2021 ◽  
Author(s):  
Tomoya Honda ◽  
Jonas Cremer ◽  
Leonardo Mancini ◽  
Zhongge Zhang ◽  
Teuta Pilizota ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Cell Size ◽  
Sensory System ◽  
Size Control ◽  
Growth Conditions ◽  
Fast Growth ◽  
Cellular Motility ◽  
E Coli ◽  
Minimum Number

To swim and navigate, motile bacteria synthesize a complex motility machinery involving flagella, motors, and a sensory system. A myriad of studies has elucidated the molecular processes involved, but less is known about the coordination of motility expression with cellular physiology: In Escherichia coli, motility genes are strongly upregulated in nutrient-poor conditions compared to nutrient-replete conditions; yet a quantitative link to cellular motility has not been developed. Here, we systematically investigate gene expression, swimming behavior, and cell growth across a broad spectrum of exponential growth condition. We establish that E. coli up-regulates the expression of motility genes at slow growth to compensate for reduction in cell size, such that the number of flagella per cell is maintained across conditions. The observed 4-5 flagella per cell is the minimum number needed to keep the majority of cells motile. This simple regulatory objective allows E. coli cells to remain motile across a broad range of growth conditions while keeping the biosynthetic and energetic demands to establish and drive the motility machinery at the minimum needed. Given the strong reduction in flagella synthesis resulting from cell size increases at fast growth, our findings also provide a novel physiological perspective on bacterial cell size control: A larger cell-size at fast growth is an efficient strategy to increase the allocation of cellular resources to the synthesis of those proteins required for fast growth, while maintaining processes such as motility which are only needed on a per-cell basis.

scholarly journals Evaluation of the Role of theopgGHOperon in Yersinia pseudotuberculosis and Its Deletion during the Emergence of Yersinia pestis

2015 ◽  
Vol 83 (9) ◽  
pp. 3638-3647 ◽  
Author(s):  
Kévin Quintard ◽  
Amélie Dewitte ◽  
Angéline Reboul ◽  
Edwige Madec ◽  
Sébastien Bontemps-Gallo ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Cell Size ◽  
Biofilm Formation ◽  
Yersinia Pseudotuberculosis ◽  
Acyl Carrier Protein ◽  
Size Control ◽  
Growth Conditions ◽  
Mammalian Host ◽  
Dickeya Dadantii ◽  
Content Type

TheopgGHoperon encodes glucosyltransferases that synthesize osmoregulated periplasmic glucans (OPGs) from UDP-glucose, using acyl carrier protein (ACP) as a cofactor. OPGs are required for motility, biofilm formation, and virulence in various bacteria. OpgH also sequesters FtsZ in order to regulate cell size according to nutrient availability.Yersinia pestis(the agent of flea-borne plague) lost theopgGHoperon during its emergence from the enteropathogenYersinia pseudotuberculosis. When expressed in OPG-negative strains ofEscherichia coliandDickeya dadantii,opgGHfromY. pseudotuberculosisrestored OPGs synthesis, motility, and virulence. However,Y. pseudotuberculosisdid not produce OPGs (i) under various growth conditions or (ii) when overexpressing itsopgGHoperon, itsgalUFoperon (governing UDP-glucose), or theopgGHoperon or Acp fromE. coli. A ΔopgGHY. pseudotuberculosisstrain showed normal motility, biofilm formation, resistance to polymyxin and macrophages, and virulence but was smaller. Consistently,Y. pestiswas smaller thanY. pseudotuberculosiswhen cultured at ≥37°C, except when the plague bacillus expressedopgGH.Y. pestisexpressingopgGHgrew normally in serum and within macrophages and was fully virulent in mice, suggesting that small cell size was not advantageous in the mammalian host. Lastly,Y. pestisexpressingopgGHwas able to infectXenopsylla cheopisfleas normally. Our results suggest an evolutionary scenario whereby an ancestralYersiniastrain lost a factor required for OPG biosynthesis but keptopgGH(to regulate cell size). TheopgGHoperon was presumably then lost because OpgH-dependent cell size control became unnecessary.

scholarly journals Environmental pH impacts division assembly and cell size in Escherichia coli

2019 ◽  
Author(s):  
Elizabeth A. Mueller ◽  
Corey S. Westfall ◽  
Petra Anne Levin
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Cell Size ◽  
Bacterial Cell ◽  
Bacterial Species ◽  
Model Organism ◽  
Size Control ◽  
Complex Trait ◽  
Genetic And Environmental Factors ◽  
Open Question

ABSTRACTCell size is a complex trait, derived from both genetic and environmental factors. Environmental determinants of bacterial cell size identified to date primarily target assembly of cytosolic components of the cell division machinery. Whether certain environmental cues also impact cell size through changes in the assembly or activity of extracytoplasmic division proteins remains an open question. Here, we identify extracellular pH as a modulator of cell division and a key determinant of cell size across evolutionarily distant bacterial species. In the Gram-negative model organism Escherichia coli, our data indicate environmental pH impacts the length at which cells divide by altering the ability of the terminal cell division protein FtsN to localize to the cytokinetic machinery and activate division. Acidic environments lead to enrichment of FtsN at the septum and activation of division at a reduced cell length, while alkaline pH inhibits FtsN localization and suppress division activation. Altogether, our work reveals a previously unappreciated role for pH in bacterial cell size control.

scholarly journals Zinc Oxide and Silver Nanoparticle Effects on Intestinal Bacteria

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2489
Author(s):  
Ami Yoo ◽  
Mengshi Lin ◽  
Azlin Mustapha
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Morphological Changes ◽  
Intestinal Bacteria ◽  
Bacterial Cells ◽  
Ag Nps ◽  
Zno Nps ◽  
Bifidobacterium Animalis ◽  
Transmission Electron

The application of nanoparticles (NPs) for food safety is increasingly being explored. Zinc oxide (ZnO) and silver (Ag) NPs are inorganic chemicals with antimicrobial and bioactive characteristics and have been widely used in the food industry. However, not much is known about the behavior of these NPs upon ingestion and whether they inhibit natural gut microflora. The objective of this study was to investigate the effects of ZnO and Ag NPs on the intestinal bacteria, namely Escherichia coli, Lactobacillus acidophilus, and Bifidobacterium animalis. Cells were inoculated into tryptic soy broth or Lactobacilli MRS broth containing 1% of NP-free solution, 0, 12, 16, 20 mM of ZnO NPs or 0, 1.8, 2.7, 4.6 mM Ag NPs, and incubated at 37 °C for 24 h. The presence and characterization of the NPs on bacterial cells were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Membrane leakage and cell viability were assessed using a UV-visible spectrophotometer and confocal electron microscope, respectively. Numbers of treated cells were within 1 log CFU/mL less than those of the controls for up to 12 h of incubation. Cellular morphological changes were observed, but many cells remained in normal shapes. Only a small amount of internal cellular contents was leaked due to the NP treatments, and more live than dead cells were observed after exposure to the NPs. Based on these results, we conclude that ZnO and Ag NPs have mild inhibitory effects on intestinal bacteria.

scholarly journals Precise regulation of the relative rates of surface area and volume synthesis in bacterial cells growing in dynamic environments

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Handuo Shi ◽  
Yan Hu ◽  
Pascal D. Odermatt ◽  
Carlos G. Gonzalez ◽  
Lichao Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Time Delay ◽  
Surface Area ◽  
Environmental Changes ◽  
Volume Ratio ◽  
Dynamic Environments ◽  
Bacterial Cells ◽  
Bacterial Growth Rate ◽  
State Size ◽  
Insight Into

AbstractThe steady-state size of bacterial cells correlates with nutrient-determined growth rate. Here, we explore how rod-shaped bacterial cells regulate their morphology during rapid environmental changes. We quantify cellular dimensions throughout passage cycles of stationary-phase cells diluted into fresh medium and grown back to saturation. We find that cells exhibit characteristic dynamics in surface area to volume ratio (SA/V), which are conserved across genetic and chemical perturbations as well as across species and growth temperatures. A mathematical model with a single fitting parameter (the time delay between surface and volume synthesis) is quantitatively consistent with our SA/V experimental observations. The model supports that this time delay is due to differential expression of volume and surface-related genes, and that the first division after dilution occurs at a tightly controlled SA/V. Our minimal model thus provides insight into the connections between bacterial growth rate and cell shape in dynamic environments.

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