An essential transcription factor, SciP, enhances robustness of Caulobacter cell cycle regulation.

TitleAn essential transcription factor, SciP, enhances robustness of Caulobacter cell cycle regulation.
Publication TypeJournal Article
Year of Publication2010
AuthorsMH Tan, JB Kozdon, X Shen, L Shapiro, and HH McAdams
JournalProceedings of the National Academy of Sciences of USA
Volume107
Issue44
Start Page18985
Pagination18985 - 18990
Date Published11/2010
Abstract

A cyclical control circuit composed of four master regulators drives the Caulobacter cell cycle. We report that SciP, a helix-turn-helix transcription factor, is an essential component of this circuit. SciP is cell cycle-controlled and co-conserved with the global cell cycle regulator CtrA in the α-proteobacteria. SciP is expressed late in the cell cycle and accumulates preferentially in the daughter swarmer cell. At least 58 genes, including many flagellar and chemotaxis genes, are regulated by a type 1 incoherent feedforward motif in which CtrA activates sciP, followed by SciP repression of ctrA and CtrA target genes. We demonstrate that SciP binds to DNA at a motif distinct from the CtrA binding motif that is present in the promoters of genes co-regulated by SciP and CtrA. SciP overexpression disrupts the balance between activation and repression of the CtrA-SciP coregulated genes yielding filamentous cells and loss of viability. The type 1 incoherent feedforward circuit motif enhances the pulse-like expression of the downstream genes, and the negative feedback to ctrA expression reduces peak CtrA accumulation. The presence of SciP in the control network enhances the robustness of the cell cycle to varying growth rates.

DOI10.1073/pnas.1014395107
Short TitleProceedings of the National Academy of Sciences of USA