Enteric bacteria such as Escherichia coli spend most of their lifetimes starved for one or more essential nutrients. To survive environmental challenges under starvation conditions these bacteria enter a non-growing state called stationary phase. The master regulator of stationary phase is the alternate primary sigma factor RpoS. In rapidly growing cells RpoS levels are low because the orphan response regulator SprE (RssB) targets RpoS for degradation by the CIpP/X protease. We have discovered that when bacteria are starved for carbon, RpoS levels increase because RpoS degradation stops. Starvation for phosphorus also results in elevated levels of RpoS, but in this case levels are elevated because of an increase in rpoS mRNA translation. In contrast starvation for nitrogen does not cause an increase in RpoS levels;rather, RpoS activity is increased. We propose a combination of genetic, biochemical, metabolomic, and computational methods to identify the key signaling and effector molecules that mediate these diverse responses to nutrient deprivation. Since RpoS is known to be important for the pathogenesis of certain bacteria, a detailed understanding of how bacteria enter and exit stationary phase may reveal chinks in the armor of these pathogens. In addition, because the pathways of central metabolism are conserved throughout biology, we think that the signals that trigger transition to a non-growing state may be conserved as well. Thus insights gained in bacteria may shed light on similar processes in eukaryotic microbes, and perhaps animal cells as well.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM065216-07
Application #
7578838
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Shapiro, Bert I
Project Start
2003-02-01
Project End
2011-01-31
Budget Start
2009-02-01
Budget End
2010-01-31
Support Year
7
Fiscal Year
2009
Total Cost
$285,262
Indirect Cost
Name
Princeton University
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
002484665
City
Princeton
State
NJ
Country
United States
Zip Code
08544
Mitchell, Angela M; Wang, Wei; Silhavy, Thomas J (2017) Novel RpoS-Dependent Mechanisms Strengthen the Envelope Permeability Barrier during Stationary Phase. J Bacteriol 199:
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Peterson, Celeste N; Levchenko, Igor; Rabinowitz, Joshua D et al. (2012) RpoS proteolysis is controlled directly by ATP levels in Escherichia coli. Genes Dev 26:548-53
Carabetta, Valerie J; Silhavy, Thomas J; Cristea, Ileana M (2010) The response regulator SprE (RssB) is required for maintaining poly(A) polymerase I-degradosome association during stationary phase. J Bacteriol 192:3713-21
Carabetta, Valerie J; Li, Tuo; Shakya, Anisha et al. (2010) Integrating Lys-N proteolysis and N-terminal guanidination for improved fragmentation and relative quantification of singly-charged ions. J Am Soc Mass Spectrom 21:1050-60
Carabetta, Valerie J; Mohanty, Bijoy K; Kushner, Sidney R et al. (2009) The response regulator SprE (RssB) modulates polyadenylation and mRNA stability in Escherichia coli. J Bacteriol 191:6812-21
Fredriksson, Asa; Ballesteros, Manuel; Peterson, Celeste N et al. (2007) Decline in ribosomal fidelity contributes to the accumulation and stabilization of the master stress response regulator sigmaS upon carbon starvation. Genes Dev 21:862-74
Gaal, Tamas; Mandel, Mark J; Silhavy, Thomas J et al. (2006) Crl facilitates RNA polymerase holoenzyme formation. J Bacteriol 188:7966-70
Peterson, Celeste N; Carabetta, Valerie J; Chowdhury, Tahmeena et al. (2006) LrhA regulates rpoS translation in response to the Rcs phosphorelay system in Escherichia coli. J Bacteriol 188:3175-81
Mandel, Mark J; Silhavy, Thomas J (2005) Starvation for different nutrients in Escherichia coli results in differential modulation of RpoS levels and stability. J Bacteriol 187:434-42

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