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bioRxiv · 10.1101/739516

Bacterial cell cycle and growth phase switch by the essential transcriptional regulator CtrA

Delaby, M.·Panis, G.·Viollier, P. H.
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Abstract

Many bacteria acquire dissemination and virulence traits in G1-phase. CtrA, an essential and conserved cell cycle transcriptional regulator identified in the dimorphic alpha-proteobacterium Caulobacter crescentus, first activates promoters in late S-phase and then mysteriously switches to different target promoters in G1-phase. We uncovered a highly conserved determinant in the DNA-binding domain (DBD) of CtrA uncoupling this promoter switch. We also show that it reprograms CtrA occupancy in stationary cells inducing a (p)ppGpp alarmone signal perceived by the RNA polymerase beta subunit. A simple side chain modification in a critical residue within the core DBD imposes opposing developmental phenotypes and transcriptional activities of CtrA. A naturally occurring polymorphism in the rickettsial DBD resembles a mutation that drives CtrA towards activation of the dispersal (G1-phase) program in Caulobacter. Hence, we propose that this determinant dictates promoter reprogramming during the growth transition of obligate intracellular rickettsia differentiating from replicative cells into dispersal cells.

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Delaby, M., Panis, G., Viollier, P. H.. 2019-08-20. Bacterial cell cycle and growth phase switch by the essential transcriptional regulator CtrA. https://doi.org/10.1101/739516

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