Discovery of the mechanism used to coordinate replication of the two Vibrio cholerae chromosomes

Bacterial genomes generally contain a single chromosome and one or more extrachromosal elements such as plasmids. The initiation of bacterial chromosome replication must be carefully checked to ensure that chromosome duplication occurs only once per cell cycle. The bacterial pathogen responsible for cholera epidemics, Vibrio cholerae, is distinctive in that it has two chromosomes. The teams led by Didier Mazel and Romain Koszul at the Institut Pasteur, in collaboration with Ole Skovgaard of Roskilde University (Denmark), have revealed an original, energy-saving mechanism known as the "replication checkpoint" that coordinates replication of the two chromosomes with the V. cholerae cell cycle. Their findings have been published in the journal The Science Advances.

In bacteria, chromosome replication must occur once per cell cycle to ensure that the number of chromosomes in the cell remains constant. This coordination occurs at the replication initiation stage, during which multiple mechanisms control the availability and activity of DnaA, the replication initiation factor that is widespread in prokaryotes. Control of plasmid replication coordination with the cell cycle is generally less strict.

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