Limits...
Inflating bacterial cells by increased protein synthesis.

Basan M, Zhu M, Dai X, Warren M, Sévin D, Wang YP, Hwa T - Mol. Syst. Biol. (2015)

Bottom Line: Here, we characterized cell sizes in a set of orthogonal growth limitations.We report that cell size and mass exhibit positive or negative dependences with growth rate depending on the growth limitation applied.In particular, synthesizing large amounts of "useless" proteins led to an inversion of the canonical, positive relation, with slow growing cells enlarged 7- to 8-fold compared to cells growing at similar rates under nutrient limitation.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland basan@imsb.biol.ethz.ch hwa@ucsd.edu.

No MeSH data available.


Related in: MedlinePlus

Cell size and content under different growth limitationsSnapshots of bacteria from different culture conditions at similar OD600 (˜0.4) and the same magnification: I. glucose (λ ≈ 0.98/h); II. mannose (λ ≈ 0.41/h); III. glucose + 8 μM Cm (λ ≈ 0.32/h); IV. LacZ OE, glucose + 15 ng/ml cTc (λ ≈ 0.25/h). Cultures under different growth limitations (II–IV) exhibit large differences in cell size at comparable growth rates.Normalized cell size distributions, as quantified by automated image analysis, for cells taken from the conditions described in panel (A). Distributions for cells grown in mannose, Cm, and LacZ OE were taken at comparable growth rates. Inset, density distributions for cell volume normalized by average cell size. When normalized by mean cell size, the different distributions appear very similar.Mean cell volume obtained under the different growth limitations plotted against the corresponding growth rate of the culture (see Appendix Table S2 for standard deviations and Appendix Table S3 for the variation between repeats and different OD600).Cellular dry mass plotted against the corresponding growth rate of the culture, for each growth perturbation. The trends of cellular dry mass closely resemble the trends exhibited by cell volume (panel C).Cellular RNA plotted against the corresponding growth rate of the culture, for each growth perturbation.DNA content per cell. The trends in DNA content, as confirmed by DAPI staining (FigEV3), also closely follow the change in cell size shown in panel (C) (see FigEV1C for the correlation plot).Cellular dry mass plotted against cell volume. A tight correlation exists between these quantities under all growth limitations.
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fig01: Cell size and content under different growth limitationsSnapshots of bacteria from different culture conditions at similar OD600 (˜0.4) and the same magnification: I. glucose (λ ≈ 0.98/h); II. mannose (λ ≈ 0.41/h); III. glucose + 8 μM Cm (λ ≈ 0.32/h); IV. LacZ OE, glucose + 15 ng/ml cTc (λ ≈ 0.25/h). Cultures under different growth limitations (II–IV) exhibit large differences in cell size at comparable growth rates.Normalized cell size distributions, as quantified by automated image analysis, for cells taken from the conditions described in panel (A). Distributions for cells grown in mannose, Cm, and LacZ OE were taken at comparable growth rates. Inset, density distributions for cell volume normalized by average cell size. When normalized by mean cell size, the different distributions appear very similar.Mean cell volume obtained under the different growth limitations plotted against the corresponding growth rate of the culture (see Appendix Table S2 for standard deviations and Appendix Table S3 for the variation between repeats and different OD600).Cellular dry mass plotted against the corresponding growth rate of the culture, for each growth perturbation. The trends of cellular dry mass closely resemble the trends exhibited by cell volume (panel C).Cellular RNA plotted against the corresponding growth rate of the culture, for each growth perturbation.DNA content per cell. The trends in DNA content, as confirmed by DAPI staining (FigEV3), also closely follow the change in cell size shown in panel (C) (see FigEV1C for the correlation plot).Cellular dry mass plotted against cell volume. A tight correlation exists between these quantities under all growth limitations.

Mentions: We characterized the dependence of cell size on growth rate for three distinct modes of growth limitations (Appendix Table S1) of E. coli K-12 cells: limitation in nutrient uptake by different growth media, limitation in protein synthesis by antibiotics, and limitation in proteome allocation by expression of useless proteins (LacZ), following recent quantitative studies of bacterial physiology (Scott et al, 2010; You et al, 2013; Hui et al, 2015). All samples were taken from exponentially growing cultures (Appendix Fig S1). In each case, the size of cells was determined via microscopy and automated image analysis (see Materials and Methods). Remarkably, cell sizes obtained for these three distinct limitations strongly diverged at comparable growth rates, as illustrated by snapshots of cells collected from cultures at similar OD600 (Fig1A), with the size distributions shown in Fig1B and Appendix Fig S2, with the means and variances of all conditions reported in Appendix Table S2. The observed size distributions were highly reproducible and independent of culture density (see Appendix Table S3, Appendix Fig S2E and F). The width of the size distributions largely results from differences in mean cell size as reported in recent single-cell studies (Taheri-Araghi et al, 2015), with the different distribution functions collapsing when normalized by the mean cell size (see inset Fig2B). Mean cell size (volume), plotted against the growth rate (GR) of the exponentially growing culture, showed distinct trends for the three limitations (Fig1C, with cell length and width presented in Appendix Fig S3, and their values listed in Appendix Table S2). While cell size decreased with nutrient limitation (green circles) in accordance with previous studies (Schaechter et al, 1958; Volkmer & Heinemann, 2011; Hill et al, 2012; Chien et al, 2012), it remained constant under sub-lethal doses of the translational inhibitor chloramphenicol (Cm, blue triangles) and increased strongly when growth was limited by the overexpression (OE) of a useless protein, LacZ (red diamonds), via a linearly inducible genetic construct (see Appendix Fig S4). Indeed, Fig1C shows that slow growing cells due to LacZ OE exhibited sizes larger than even the largest cells observed for the fastest growing wild-type cells cultured in rich media.


Inflating bacterial cells by increased protein synthesis.

Basan M, Zhu M, Dai X, Warren M, Sévin D, Wang YP, Hwa T - Mol. Syst. Biol. (2015)

Cell size and content under different growth limitationsSnapshots of bacteria from different culture conditions at similar OD600 (˜0.4) and the same magnification: I. glucose (λ ≈ 0.98/h); II. mannose (λ ≈ 0.41/h); III. glucose + 8 μM Cm (λ ≈ 0.32/h); IV. LacZ OE, glucose + 15 ng/ml cTc (λ ≈ 0.25/h). Cultures under different growth limitations (II–IV) exhibit large differences in cell size at comparable growth rates.Normalized cell size distributions, as quantified by automated image analysis, for cells taken from the conditions described in panel (A). Distributions for cells grown in mannose, Cm, and LacZ OE were taken at comparable growth rates. Inset, density distributions for cell volume normalized by average cell size. When normalized by mean cell size, the different distributions appear very similar.Mean cell volume obtained under the different growth limitations plotted against the corresponding growth rate of the culture (see Appendix Table S2 for standard deviations and Appendix Table S3 for the variation between repeats and different OD600).Cellular dry mass plotted against the corresponding growth rate of the culture, for each growth perturbation. The trends of cellular dry mass closely resemble the trends exhibited by cell volume (panel C).Cellular RNA plotted against the corresponding growth rate of the culture, for each growth perturbation.DNA content per cell. The trends in DNA content, as confirmed by DAPI staining (FigEV3), also closely follow the change in cell size shown in panel (C) (see FigEV1C for the correlation plot).Cellular dry mass plotted against cell volume. A tight correlation exists between these quantities under all growth limitations.
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fig01: Cell size and content under different growth limitationsSnapshots of bacteria from different culture conditions at similar OD600 (˜0.4) and the same magnification: I. glucose (λ ≈ 0.98/h); II. mannose (λ ≈ 0.41/h); III. glucose + 8 μM Cm (λ ≈ 0.32/h); IV. LacZ OE, glucose + 15 ng/ml cTc (λ ≈ 0.25/h). Cultures under different growth limitations (II–IV) exhibit large differences in cell size at comparable growth rates.Normalized cell size distributions, as quantified by automated image analysis, for cells taken from the conditions described in panel (A). Distributions for cells grown in mannose, Cm, and LacZ OE were taken at comparable growth rates. Inset, density distributions for cell volume normalized by average cell size. When normalized by mean cell size, the different distributions appear very similar.Mean cell volume obtained under the different growth limitations plotted against the corresponding growth rate of the culture (see Appendix Table S2 for standard deviations and Appendix Table S3 for the variation between repeats and different OD600).Cellular dry mass plotted against the corresponding growth rate of the culture, for each growth perturbation. The trends of cellular dry mass closely resemble the trends exhibited by cell volume (panel C).Cellular RNA plotted against the corresponding growth rate of the culture, for each growth perturbation.DNA content per cell. The trends in DNA content, as confirmed by DAPI staining (FigEV3), also closely follow the change in cell size shown in panel (C) (see FigEV1C for the correlation plot).Cellular dry mass plotted against cell volume. A tight correlation exists between these quantities under all growth limitations.
Mentions: We characterized the dependence of cell size on growth rate for three distinct modes of growth limitations (Appendix Table S1) of E. coli K-12 cells: limitation in nutrient uptake by different growth media, limitation in protein synthesis by antibiotics, and limitation in proteome allocation by expression of useless proteins (LacZ), following recent quantitative studies of bacterial physiology (Scott et al, 2010; You et al, 2013; Hui et al, 2015). All samples were taken from exponentially growing cultures (Appendix Fig S1). In each case, the size of cells was determined via microscopy and automated image analysis (see Materials and Methods). Remarkably, cell sizes obtained for these three distinct limitations strongly diverged at comparable growth rates, as illustrated by snapshots of cells collected from cultures at similar OD600 (Fig1A), with the size distributions shown in Fig1B and Appendix Fig S2, with the means and variances of all conditions reported in Appendix Table S2. The observed size distributions were highly reproducible and independent of culture density (see Appendix Table S3, Appendix Fig S2E and F). The width of the size distributions largely results from differences in mean cell size as reported in recent single-cell studies (Taheri-Araghi et al, 2015), with the different distribution functions collapsing when normalized by the mean cell size (see inset Fig2B). Mean cell size (volume), plotted against the growth rate (GR) of the exponentially growing culture, showed distinct trends for the three limitations (Fig1C, with cell length and width presented in Appendix Fig S3, and their values listed in Appendix Table S2). While cell size decreased with nutrient limitation (green circles) in accordance with previous studies (Schaechter et al, 1958; Volkmer & Heinemann, 2011; Hill et al, 2012; Chien et al, 2012), it remained constant under sub-lethal doses of the translational inhibitor chloramphenicol (Cm, blue triangles) and increased strongly when growth was limited by the overexpression (OE) of a useless protein, LacZ (red diamonds), via a linearly inducible genetic construct (see Appendix Fig S4). Indeed, Fig1C shows that slow growing cells due to LacZ OE exhibited sizes larger than even the largest cells observed for the fastest growing wild-type cells cultured in rich media.

Bottom Line: Here, we characterized cell sizes in a set of orthogonal growth limitations.We report that cell size and mass exhibit positive or negative dependences with growth rate depending on the growth limitation applied.In particular, synthesizing large amounts of "useless" proteins led to an inversion of the canonical, positive relation, with slow growing cells enlarged 7- to 8-fold compared to cells growing at similar rates under nutrient limitation.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland basan@imsb.biol.ethz.ch hwa@ucsd.edu.

No MeSH data available.


Related in: MedlinePlus