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Journal of Bacteriology, August 2009, p. 4732-4749, Vol. 191, No. 15
0021-9193/09/$08.00+0     doi:10.1128/JB.00136-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Conserved Network of Proteins Essential for Bacterial Viability{triangledown} ,{dagger}

Jennifer I. Handford,1,{ddagger} Bérengère Ize,1,2,{ddagger},§ Grant Buchanan,3 Gareth P. Butland,4,5 Jack Greenblatt,5 Andrew Emili,5 and Tracy Palmer3*

Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich NR4 7UH, United Kingdom,1 School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom,2 Division of Molecular and Environmental Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom,3 Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California, 94720,4 Banting and Best Department of Medical Research, Terrence Donnelly Center for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada M5S 3E15

Received 31 January 2009/ Accepted 7 April 2009

The yjeE, yeaZ, and ygjD genes are highly conserved in the genomes of eubacteria, and ygjD orthologs are also found throughout the Archaea and eukaryotes. In this study, we have constructed conditional expression strains for each of these genes in the model organism Escherichia coli K12. We show that each gene is essential for the viability of E. coli under laboratory growth conditions. Growth of the conditional strains under nonpermissive conditions results in dramatic changes in cell ultrastructure. Deliberate repression of the expression of yeaZ results in cells with highly condensed nucleoids, while repression of yjeE and ygjD expression results in at least a proportion of very enlarged cells with an unusual peripheral distribution of DNA. Each of the three conditional expression strains can be complemented by multicopy clones harboring the rstA gene, which encodes a two-component-system response regulator, strongly suggesting that these proteins are involved in the same essential cellular pathway. The results of bacterial two-hybrid experiments show that YeaZ can interact with both YjeE and YgjD but that YgjD is the preferred interaction partner. The results of in vitro experiments indicate that YeaZ mediates the proteolysis of YgjD, suggesting that YeaZ and YjeE act as regulators to control the activity of this protein. Our results are consistent with these proteins forming a link between DNA metabolism and cell division.

* Corresponding author. Mailing address: Division of Molecular Microbiology, College of Life Sciences, Dow Street, University of Dundee, Dundee DD1 5EH, United Kingdom. Phone: 44-01382 386464. Fax: 44-01382 388216. E-mail: t.palmer{at}dundee.ac.uk

{triangledown} Published ahead of print on 17 April 2009.

{dagger} Supplemental material for this article may be found at http://jb.asm.org/.

{ddagger} These authors contributed equally to this work.

§ Present address: Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, UPR 9027, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.

Journal of Bacteriology, August 2009, p. 4732-4749, Vol. 191, No. 15
0021-9193/09/$08.00+0     doi:10.1128/JB.00136-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Related articles in JB:

Grasping at Shadows: Revealing the Elusive Nature of Essential Genes
Tarek Msadek
JB 2009 191: 4701-4704. [Full Text]  



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  • Msadek, T. (2009). Grasping at Shadows: Revealing the Elusive Nature of Essential Genes. J. Bacteriol. 191: 4701-4704 [Full Text]  


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