Email updates

Keep up to date with the latest news and content from BMC Microbiology and BioMed Central.

Open Access Highly Accessed Research article

The terminal region of the E. coli chromosome localises at the periphery of the nucleoid

Jean-Christophe Meile12, Romain Mercier123, Mathieu Stouf12, Carine Pages12, Jean-Yves Bouet12* and François Cornet12*

Author affiliations

1 Université de Toulouse; Université Paul Sabatier; Laboratoire de Microbiologie et Génétique Moléculaires; F-31000 Toulouse; France

2 Centre National de la Recherche Scientifique; LMGM; F-31000 Toulouse; France

3 Current Address: Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle, 2nd Floor, Catherine Cookson Building, Framlington Place, Newcastle, NE2 4HH, UK

For all author emails, please log on.

Citation and License

BMC Microbiology 2011, 11:28  doi:10.1186/1471-2180-11-28

Published: 2 February 2011

Abstract

Background

Bacterial chromosomes are organised into a compact and dynamic structures termed nucleoids. Cytological studies in model rod-shaped bacteria show that the different regions of the chromosome display distinct and specific sub-cellular positioning and choreographies during the course of the cell cycle. The localisation of chromosome loci along the length of the cell has been described. However, positioning of loci across the width of the cell has not been determined.

Results

Here, we show that it is possible to assess the mean positioning of chromosomal loci across the width of the cell using two-dimension images from wide-field fluorescence microscopy. Observed apparent distributions of fluorescent-tagged loci of the E. coli chromosome along the cell diameter were compared with simulated distributions calculated using a range of cell width positioning models. Using this method, we detected the migration of chromosome loci towards the cell periphery induced by production of the bacteriophage T4 Ndd protein. In the absence of Ndd production, loci outside the replication terminus were located either randomly along the nucleoid width or towards the cell centre whereas loci inside the replication terminus were located at the periphery of the nucleoid in contrast to other loci.

Conclusions

Our approach allows to reliably observing the positioning of chromosome loci along the width of E. coli cells. The terminal region of the chromosome is preferentially located at the periphery of the nucleoid consistent with its specific roles in chromosome organisation and dynamics.