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Feedback control of a master bacterial cell-cycle regulator.
I J Domian1, A Reisenauer, L Shapiro
1Department of Developmental Biology, Beckman Center, B300, Stanford University School of Medicine, Stanford, CA 94305-5329, USA.
Summary
The transcriptional regulator CtrA controls Caulobacter crescentus cell-cycle events through two promoters with feedback loops. This regulation ensures precise timing and location of CtrA activity for essential cellular processes.
Area of Science:
- Microbiology
- Molecular Biology
- Cell Biology
Background:
- CtrA is a key transcriptional regulator governing cell-cycle progression in Caulobacter crescentus.
- Its activity is tightly controlled through temporal and spatial mechanisms, including transcription, phosphorylation, and proteolysis.
Purpose of the Study:
- To investigate the transcriptional regulation of ctrA expression during the Caulobacter crescentus cell cycle.
- To elucidate the feedback mechanisms controlling CtrA activity and its role in cell-cycle events.
Main Methods:
- Analysis of ctrA gene expression using two distinct promoters (P1 and P2).
- Investigation of CtrA-mediated feedback regulation on these promoters.
- Identification of CtrA binding sites within the promoter regions using footprinting assays.
Main Results:
- CtrA expression is controlled by two promoters: P1 (early predivisional cell) and P2 (late predivisional cell).
- P1 is negatively regulated by CtrA, while P2 is positively regulated by CtrA.
- CtrA protein binds to conserved sites within both P1 and P2 promoters.
Conclusions:
- Two coupled transcriptional feedback loops involving P1 and P2 promoters regulate CtrA activity.
- This intricate regulatory system, combined with post-translational modifications, ensures precise temporal and spatial control of CtrA.
- This control is essential for orchestrating key cell-cycle events in Caulobacter crescentus.