Cell division must be coordinated with chromosome replication and segregation to ensure the faithful transmission of genetic information during proliferation. In most bacteria, assembly of the division apparatus, the divisome, starts with the polymerization of a tubulin homologue, FtsZ, into a ring-like structure at mid-cell, the Z-ring1. It typically occurs at half of the cell cycle when most of the replication and segregation cycle of the unique chromosome they generally harbour is achieved2. The chromosome itself participates in the regulation of cell division, at least in part because it serves as a scaffold to position FtsZ polymerization antagonists3. However, about 10% of bacteria have more than one chromosome4, which raises questions about the way they license cell division3. For instance, the genome of Vibrio cholerae, the agent of cholera, is divided between a 3 Mbp replicon that originates from the chromosome of its mono-chromosomal ancestor, Chr1, and a 1 Mbp plasmid-derived replicon, Chr2 (ref. 5). Here, we show that Chr2 harbours binding motifs for an inhibitor of Z-ring formation, which helps accurately position the V. cholerae divisome at mid-cell and postpones its assembly to the very end of the cell cycle.
The authors thank M.-E. Val and D. Mazel for the gift of strain MCH1 and N. Dubarry and the other team members for insightful comments. The authors acknowledge financial support from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013 grant agreement no. 281590), the Fondation Bettencourt Schueller (2012 Coup d'Elan award) and the ‘Lidex-Biologie Intégrative des Génomes’ project of the Paris-Saclay IDEX (ANR-11-IDEX-0003-02). The light microscopy facility of Imagerie-Gif is a member of the Infrastructures en Biologie Santé et Agronomie (IBiSA), and is supported by the French national Research Agency under Investments for the Future programmes ‘France-BioImaging’ and the Labex ‘Saclay Plant Science’ (ANR-10-INSB-04-01 and ANR-11-IDEX-0003-02, respectively).
3D FtsZ-mEos2 structures throughout the V. cholerae cell cycle observed using PALM. Cells grown in M9 minimal medium supplemented with 0.2% fructose and 1 µg ml−1 thiamine.
Time-lapse analysis of MinD-YGFP localization in V. cholerae cells. One frame was taken every 20 seconds. Cells grown in M9 minimal medium supplemented with 0.2% fructose and 1 µg ml−1 thiamine
Time-lapse analysis of MinD-YGFP and FtsZ-RFPT localization in V. cholerae cells. One frame was taken every 20 seconds. Cells grown in M9 minimal medium supplemented with 0.2% fructose and 1 µg ml−1 thiamine.
Mini-cell formation in MCH1. One frame was taken every 3 minutes. Cells were grown in LB
Formation of an anucleate cell after a highly asymmetric division in MCH1. Genomic DNA is labelled with a HUα-RFPT fusion. One frame was taken every 3 minutes. Cells grown in M9 minimal medium supplemented with 0.2% fructose and 1 µg ml−1 thiamine.