The goal of this proposal is to define the regulatory mechanisms that control the bacterial cell cycle and to understand how these mechanisms function within an integrated system. We have shown that Caulobacter exerts exquisite spatial and temporal control of its cell cycle by the use of transcriptional and proteolytic networks integrated with dynamic subcellular protein localization. Key to cell cycle control, a small number of master transcriptional regulators orchestrate cell cycle progression. A two component phospho-signaling pathway, involving the polarly-localized CckA histidine kinase, mediates the activation of the CtrA master regulator whose function is to regulate the genes involved in polar morphogenesis and the biogenesis of the cell division apparatus. Using robotic high throughput screens for genes involved in protein localization, we identified the DivL kinase for the localization of the CckA histidine kinase, and the CpaE pili protein for the localization of the PleC histidine kinase that is essential for polar morphogenesis. We will explore the mechanism of polar localization of these critical kinases and determine how it is related to their function within the cell cycle regulatory circuit. To understand the cell cycle integration of transcriptional regulation, we will define the mechanism of action of the newly identified SciP transcriptional regulator that functions as a repressor of CtrA activated genes at a specific time in the cell cycle, and the novel CrfA non-coding RNA that modifies the cell cycle regulatory circuitry in response to nutrient deprivation. Finally, the mid-cell establishment of the FtsZ cytokinetic ring is dependent on signals from the cell poles and is an integral component of the core cell cycle circuitry. Accordingly, we will explore the temporally regulated localization, assembly, and disassembly of the divisome, as a function of the cell cycle.

Public Health Relevance

We examine the molecular mechanisms of each of the consecutive steps in the bacterial cell cycle and then elucidate how these individual events are integrated into a functional system. This approach has allowed the identification of novel mechanisms that coordinate the temporal and spatial control of cell cycle progression, leading to the identification of new antibiotic targets and ultimately the design and development of a new class of antibiotics.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Prokaryotic Cell and Molecular Biology Study Section (PCMB)
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Hamlet, Michelle R
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Stanford University
Anatomy/Cell Biology
Schools of Medicine
United States
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Mann, Thomas H; Shapiro, Lucy (2018) Integration of cell cycle signals by multi-PAS domain kinases. Proc Natl Acad Sci U S A 115:E7166-E7173
Perez, Adam M; Mann, Thomas H; Lasker, Keren et al. (2017) A Localized Complex of Two Protein Oligomers Controls the Orientation of Cell Polarity. MBio 8:
Schrader, Jared M; Li, Gene-Wei; Childers, W Seth et al. (2016) Dynamic translation regulation in Caulobacter cell cycle control. Proc Natl Acad Sci U S A 113:E6859-E6867
Lasker, Keren; Schrader, Jared M; Men, Yifei et al. (2016) CauloBrowser: A systems biology resource for Caulobacter crescentus. Nucleic Acids Res 44:D640-5
Ricci, Dante P; Melfi, Michael D; Lasker, Keren et al. (2016) Cell cycle progression in Caulobacter requires a nucleoid-associated protein with high AT sequence recognition. Proc Natl Acad Sci U S A 113:E5952-E5961
Mann, Thomas H; Seth Childers, W; Blair, Jimmy A et al. (2016) A cell cycle kinase with tandem sensory PAS domains integrates cell fate cues. Nat Commun 7:11454
Lasker, Keren; Mann, Thomas H; Shapiro, Lucy (2016) An intracellular compass spatially coordinates cell cycle modules in Caulobacter crescentus. Curr Opin Microbiol 33:131-139
Schrader, Jared M; Shapiro, Lucy (2015) Synchronization of Caulobacter crescentus for investigation of the bacterial cell cycle. J Vis Exp :
Zhou, Bo; Schrader, Jared M; Kalogeraki, Virginia S et al. (2015) The global regulatory architecture of transcription during the Caulobacter cell cycle. PLoS Genet 11:e1004831
Ptacin, Jerod L; Gahlmann, Andreas; Bowman, Grant R et al. (2014) Bacterial scaffold directs pole-specific centromere segregation. Proc Natl Acad Sci U S A 111:E2046-55

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