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Proc Natl Acad Sci U S A. 2016 Nov 1;113(44):12550-12555. Epub 2016 Oct 17.

In-phase oscillation of global regulons is orchestrated by a pole-specific organizer.

Author information

1
School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695016, Kerala, India.
2
Department of Microbiology and Molecular Medicine, Institute of Genetics & Genomics in Geneva, University of Geneva Medical School, Geneva CH-1211, Switzerland.
3
Department of Microbiology and Molecular Medicine, Institute of Genetics & Genomics in Geneva, University of Geneva Medical School, Geneva CH-1211, Switzerland patrick.viollier@unige.ch sunish@iisertvm.ac.in.
4
School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695016, Kerala, India; patrick.viollier@unige.ch sunish@iisertvm.ac.in.

Abstract

Cell fate determination in the asymmetric bacterium Caulobacter crescentus (Caulobacter) is triggered by the localization of the developmental regulator SpmX to the old (stalked) cell pole during the G1→S transition. Although SpmX is required to localize and activate the cell fate-determining kinase DivJ at the stalked pole in Caulobacter, in cousins such as Asticcacaulis, SpmX directs organelle (stalk) positioning and possibly other functions. We define the conserved σ54-dependent transcriptional activator TacA as a global regulator in Caulobacter whose activation by phosphorylation is indirectly down-regulated by SpmX. Using a combination of forward genetics and cytological screening, we uncover a previously uncharacterized and polarized component (SpmY) of the TacA phosphorylation control system, and we show that SpmY function and localization are conserved. Thus, SpmX organizes a site-specific, ancestral, and multifunctional regulatory hub integrating the in-phase oscillation of two global transcriptional regulators, CtrA (the master cell cycle transcriptional regulator A) and TacA, that perform important cell cycle functions.

KEYWORDS:

Caulobacter crescentus; SpmX; cell cycle; α-proteobacteria; σ54

PMID:
27791133
PMCID:
PMC5098664
DOI:
10.1073/pnas.1610723113
[Indexed for MEDLINE]
Free PMC Article

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