Exposure of bacteria to diverse growth-limiting stresses induces the synthesis of a large set of proteins that protect the cell against future, potentially lethal stresses. This general stress response brings about a special physiological state which enhances survival in the natural environment, in foods, and in some pathogenic interactions. Among Bacillus subtilis and related Gram positive pathogens, this response is governed by the ?B transcription factor. Loss of ?B function causes increased sensitivity to multiple stresses, including acid, antibiotic, cold, heat, osmotic, and oxidative stress. Our long term objective is to understand this response using B. subtilis as a model, beginning with the sensors which detect the different stresses, extending through the signal transduction network which conveys this information to ?B, and ending with the physiological role of genes under ?B control. This proposal addresses the signaling network itself, which functions by the "partner switching" mechanism in which key protein interactions are controlled by serine or threonine phosphorylation. This mechanism appears to be ancient, very plastic, and widespread among eubacteria. Study of this mechanism in B. subtilis should therefore help understand principles governing a broad array of signaling pathways. Here it activates ?B in response to two classes of stresses: (i) energy stress, including starvation for carbon, phosphate, or oxygen;and (ii) environmental stress, including acid, ethanol, heat, or salt. These two classes are conveyed to ?B by separate signaling pathways, each terminating with a differentially regulated PP2C phosphatase and each converging on the direct regulators of ?B, the RsbV anti-anti-? and the RsbW anti-?, which form one partner switching module. The energy branch consists of the RsbP phosphatase (with a PAS domain important for signaling) and RsbQ, a predicted hydrolase that is also required. The environmental branch has eight regulators, some redundant, and all join to activate the RsbU phosphatase via a second, atypical partner switching module. Six of these regulators co-purify from cell extracts in a large (>700 kDa) complex, and three form a simplified core amenable to analysis in vitro and in vivo.
Our specific aims use a combined genetic, biochemical and structural approach to address three questions: (1) What is the mechanism of energy signaling;(2) What is the mechanism of environmental signaling;and (3) What is the role of positive and negative feedback in the ?B network?
|Gaidenko, Tatiana A; Price, Chester W (2014) Genetic evidence for a phosphorylation-independent signal transduction mechanism within the Bacillus subtilis stressosome. PLoS One 9:e90741|
|Eymann, Christine; Schulz, Stephan; Gronau, Katrin et al. (2011) In vivo phosphorylation patterns of key stressosome proteins define a second feedback loop that limits activation of Bacillus subtilis ýýB. Mol Microbiol 80:798-810|
|Gaidenko, Tatiana A; Bie, Xiaomei; Baldwin, Enoch P et al. (2011) Substitutions in the presumed sensing domain of the Bacillus subtilis stressosome affect its basal output but not response to environmental signals. J Bacteriol 193:3588-97|
|Nadezhdin, Eugene V; Brody, Margaret S; Price, Chester W (2011) An ýý/ýý hydrolase and associated Per-ARNT-Sim domain comprise a bipartite sensing module coupled with diverse output domains. PLoS One 6:e25418|
|Shin, Ji-Hyun; Brody, Margaret S; Price, Chester W (2010) Physical and antibiotic stresses require activation of the RsbU phosphatase to induce the general stress response in Listeria monocytogenes. Microbiology 156:2660-9|
|Brody, Margaret S; Stewart, Valley; Price, Chester W (2009) Bypass suppression analysis maps the signalling pathway within a multidomain protein: the RsbP energy stress phosphatase 2C from Bacillus subtilis. Mol Microbiol 72:1221-34|
|Shin, Ji-Hyun; Price, Chester W (2007) The SsrA-SmpB ribosome rescue system is important for growth of Bacillus subtilis at low and high temperatures. J Bacteriol 189:3729-37|
|Igoshin, Oleg A; Brody, Margaret S; Price, Chester W et al. (2007) Distinctive topologies of partner-switching signaling networks correlate with their physiological roles. J Mol Biol 369:1333-52|
|Igoshin, Oleg A; Price, Chester W; Savageau, Michael A (2006) Signalling network with a bistable hysteretic switch controls developmental activation of the sigma transcription factor in Bacillus subtilis. Mol Microbiol 61:165-84|
|Gaidenko, Tatiana A; Kim, Tae-Jong; Weigel, Andrea L et al. (2006) The blue-light receptor YtvA acts in the environmental stress signaling pathway of Bacillus subtilis. J Bacteriol 188:6387-95|
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