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Cell Rep. 2014 Nov 20;9(4):1528-37. doi: 10.1016/j.celrep.2014.10.040. Epub 2014 Nov 13.

Systematic perturbation of cytoskeletal function reveals a linear scaling relationship between cell geometry and fitness.

Author information

1
Bio-X Program, Stanford University, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University, Stanford, CA 94305, USA. Electronic address: rmonds@syntheticgenomics.com.
2
Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.
3
Biophysics Program, Stanford University, Stanford, CA 94305, USA.
4
Bio-X Program, Stanford University, Stanford, CA 94305, USA.
5
Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA.
6
Bio-X Program, Stanford University, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address: kchuang@stanford.edu.

Abstract

Diversification of cell size is hypothesized to have occurred through a process of evolutionary optimization, but direct demonstrations of causal relationships between cell geometry and fitness are lacking. Here, we identify a mutation from a laboratory-evolved bacterium that dramatically increases cell size through cytoskeletal perturbation and confers a large fitness advantage. We engineer a library of cytoskeletal mutants of different sizes and show that fitness scales linearly with respect to cell size over a wide physiological range. Quantification of the growth rates of single cells during the exit from stationary phase reveals that transitions between "feast-or-famine" growth regimes are a key determinant of cell-size-dependent fitness effects. We also uncover environments that suppress the fitness advantage of larger cells, indicating that cell-size-dependent fitness effects are subject to both biophysical and metabolic constraints. Together, our results highlight laboratory-based evolution as a powerful framework for studying the quantitative relationships between morphology and fitness.

PMID:
25456141
DOI:
10.1016/j.celrep.2014.10.040
[Indexed for MEDLINE]
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