Proper spatial and temporal regulation of the cell cycle is crucial to the survival and proliferation of all organisms. To ensure stable, orderly cell cycle progression, cells employ complex genetic circuits. The architecture, operation, and design principles of such circuits remain only poorly understood. The bacterium Caulobacter crescentus provides an experimentally tractable system for studying genetic circuits and for elucidating fundamental molecular mechanisms of cell cycle regulation. In C. crescentus the cell cycle is driven by the periodic rise and fall in activity of a master regulator, CtrA. Active CtrA directly regulates the expression of nearly 100 genes, many of which coordinate cell division. CtrA also directly binds to and silences the origin of replication. Cell cycle progression therefore requires oscillations in CtrA activity - it must be cleared from the cell to permit DNA replication, but must accumulate to drive cell division. The outline of a genetic circuit controlling CtrA is in place, but does not yet fully account for the dynamics of CtrA activity. Additional components and levels of regulation must exist. The goal of this project is to define the complete molecular circuitry that controls CtrA activity and hence ensures orderly progression through the cell cycle. To this end, we will: (i) map the pathways that regulate phosphorylation and dephosphorylation of CtrA, (ii) elucidate how cells control the sub-cellular localization and activity of CckA, the primary phosphodonor for CtrA (iii) examine how multiple transcriptional feedback loops collaborate to precisely control the induction dynamics of CtrA, and (iv) identify and characterize additional factors that regulate CtrA activity. These studies will help to unveil how cells use multiple modes of regulation to successfully navigate their cell cycle. In addition, this work will help to reveal the general design and operating principles of genetic circuits, which underlie regulatory processes throughout biology. Finally, a better understanding of how bacteria regulate the cell cycle may help guide the development of new antibiotics, a problem of increasing public-health relevance.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM082899-05
Application #
8245739
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Hamlet, Michelle R
Project Start
2008-04-01
Project End
2013-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
5
Fiscal Year
2012
Total Cost
$288,032
Indirect Cost
$111,614
Name
Massachusetts Institute of Technology
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
001425594
City
Cambridge
State
MA
Country
United States
Zip Code
02139
Badrinarayanan, Anjana; Le, Tung B K; Spille, Jan-Hendrik et al. (2017) Global analysis of double-strand break processing reveals in vivo properties of the helicase-nuclease complex AddAB. PLoS Genet 13:e1006783
García-Bayona, Leonor; Guo, Monica S; Laub, Michael T (2017) Contact-dependent killing by Caulobacter crescentus via cell surface-associated, glycine zipper proteins. Elife 6:
Wang, Xindan; Brandão, Hugo B; Le, Tung B K et al. (2017) Bacillus subtilis SMC complexes juxtapose chromosome arms as they travel from origin to terminus. Science 355:524-527
Tran, Ngat T; Laub, Michael T; Le, Tung B K (2017) SMC Progressively Aligns Chromosomal Arms in Caulobacter crescentus but Is Antagonized by Convergent Transcription. Cell Rep 20:2057-2071
Le, Tung Bk; Laub, Michael T (2016) Transcription rate and transcript length drive formation of chromosomal interaction domain boundaries. EMBO J 35:1582-95
Liu, Jing; Francis, Laura I; Jonas, Kristina et al. (2016) ClpAP is an auxiliary protease for DnaA degradation in Caulobacter crescentus. Mol Microbiol 102:1075-1085
Aakre, Christopher D; Herrou, Julien; Phung, Tuyen N et al. (2015) Evolving new protein-protein interaction specificity through promiscuous intermediates. Cell 163:594-606
Lubin, Emma A; Henry, Jonathan T; Fiebig, Aretha et al. (2015) Identification of the PhoB Regulon and Role of PhoU in the Phosphate Starvation Response of Caulobacter crescentus. J Bacteriol 198:187-200
Badrinarayanan, Anjana; Le, Tung B K; Laub, Michael T (2015) Rapid pairing and resegregation of distant homologous loci enables double-strand break repair in bacteria. J Cell Biol 210:385-400
Salazar, Michael E; Laub, Michael T (2015) Temporal and evolutionary dynamics of two-component signaling pathways. Curr Opin Microbiol 24:7-14

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