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Open Access Highly Accessed Research article

Single-cell time-lapse analysis of depletion of the universally conserved essential protein YgjD

Tobias Bergmiller1*, Rafael Peña-Miller2, Alexander Boehm3 and Martin Ackermann1

Author Affiliations

1 Department of Environmental Sciences, ETH Zurich, Switzerland, and Department of Environmental Microbiology, Eawag, Switzerland

2 Biosciences, University of Exeter, Exeter, UK

3 Institut für Molekulare Infektionsbiologie, University of Wuerzburg, Germany

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BMC Microbiology 2011, 11:118  doi:10.1186/1471-2180-11-118

Published: 27 May 2011

Abstract

Background

The essential Escherichia coli gene ygjD belongs to a universally conserved group of genes whose function has been the focus of a number of recent studies. Here, we put ygjD under control of an inducible promoter, and used time-lapse microscopy and single cell analysis to investigate the phenotypic consequences of the depletion of YgjD protein from growing cells.

Results

We show that loss of YgjD leads to a marked decrease in cell size and termination of cell division. The transition towards smaller size occurs in a controlled manner: cell elongation and cell division remain coupled, but cell size at division decreases. We also find evidence that depletion of YgjD leads to the synthesis of the intracellular signaling molecule (p)ppGpp, inducing a cellular reaction resembling the stringent response. Concomitant deletion of the relA and spoT genes - leading to a strain that is uncapable of synthesizing (p)ppGpp - abrogates the decrease in cell size, but does not prevent termination of cell division upon YgjD depletion.

Conclusions

Depletion of YgjD protein from growing cells leads to a decrease in cell size that is contingent on (p)ppGpp, and to a termination of cell division. The combination of single-cell timelapse microscopy and statistical analysis can give detailed insights into the phenotypic consequences of the loss of essential genes, and can thus serve as a new tool to study the function of essential genes.