Phosphate starvation decouples cell differentiation from DNA replication control in the dimorphic bacterium < i > Caulobacter crescentus < /i >

by Joel Hallgren, Kira Koonce, Michele Felletti, Julien Mortier, Eloisa Turco, Kristina Jonas Upon nutrient depletion, bacteria stop proliferating and undergo physiological and morphological changes to ensure their survival. Yet, how these processes are coordinated in response to distinct starvation conditions is poorly understood. Here we compare the cellular responses ofCaulobacter crescentus to carbon (C), nitrogen (N) and phosphorus (P) starvation conditions. We find that DNA replication initiation and abundance of the replication initiator DnaA are, under all three starvation conditions, regulated by a common mechanism involving the inhibition of DnaA translation. By contrast, cell differentiation from a motile swarmer cell to a sessile stalked cell is regulated differently under the three starvation conditions. During C and N starvation, production of the signaling molecules (p)ppGpp is required to arrest cell development in the motile swarmer stage. By contrast, our data suggest that low (p)ppGpp levels under P starvation allow P-starved swarmer cells to differentiate into sessile stalked cells. Further, we show that limited DnaA availability, and consequently absence of DNA replication initiation, is the main reason that prevents P-starved stalked cells from completing the cell cycle. Together, our findings demonstrate thatC.crescentus decouples cell differentiation from DNA replication initiation under certain starvation conditions, two otherwise intimately coupled ...
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research