title: In-phase oscillation of global regulons is orchestrated by a pole-specific organizer.
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.
authors: School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695016, Kerala, India.
authors: Balaganesh
authors: B
authors: Janakiraman
authors: Department of Microbiology and Molecular Medicine, Institute of Genetics & Genomics in Geneva, University of Geneva Medical School, Geneva CH-1211, Switzerland.
authors: Johann
authors: J
authors: Mignolet
authors: School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695016, Kerala, India.
authors: Sharath
authors: S
authors: Narayanan
authors: 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.
authors: Patrick H
authors: PH
authors: Viollier
authors: School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695016, Kerala, India; patrick.viollier@unige.ch sunish@iisertvm.ac.in.
authors: Sunish Kumar
authors: 0000-0001-8729-263X
authors: SK
authors: Radhakrishnan
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D016935:Caulobacter crescentus / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D010766:Phosphorylation; D018085:Regulon / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D015534:Trans-Activators
keywords: Caulobacter crescentus; SpmX; cell cycle; α-proteobacteria; σ54