TipN's involvement with centromere segregation in Caulobacter crescentus.

Bacteria's ability to maintain chromosomal integrity throughout their life cycle is crucial for their survival. In , the polar factor TipN has been proposed to be involved with the partitioning system ParABS. However, cells with knocked out display subtle segregation defects. We hypothesized that TipN's role with segregation is obscured by other forces that are ParABS-independent. To test our hypothesis, we removed one of those forces - chromosome replication - and analyzed the role of TipN with ParA. We first demonstrate that ParA retains its ability to transport the centromeric region from the stalked pole to the opposite pole in the absence of chromosome replication. Our data revealed that in the absence of chromosome replication, TipN becomes essential for ParA's ability to transport . Furthermore, we identify a potential connection between the replication initiator DnaA and TipN. Although TipN is not essential for viability, knockout cells lose viability when the regulation of DnaA levels is altered. Our data suggest that the DnaA-dependent susceptibility of knockout cells is connected to segregation. Collectively, this work provides insights into the complex regulation involved in the coordination of chromosome replication and segregation in bacteria.