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The complex logic of stringent response regulation in Caulobacter crescentus : starvation signalling in an oligotrophic environment
Author(s) -
Boutte Cara C.,
Crosson Sean
Publication year - 2011
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2011.07602.x
Subject(s) - caulobacter crescentus , stringent response , biology , rna polymerase , transcription (linguistics) , microbiology and biotechnology , bacteria , escherichia coli , ribosomal protein , starvation response , biochemistry , ribosome , gene , rna , genetics , bacterial protein , linguistics , philosophy
Summary Bacteria rapidly adapt to nutritional changes via the stringent response, which entails starvation‐induced synthesis of the small molecule, ppGpp, by RelA/SpoT homologue (Rsh) enzymes. Binding of ppGpp to RNA polymerase modulates the transcription of hundreds of genes and remodels the physiology of the cell. Studies of the stringent response have primarily focused on copiotrophic bacteria such as Escherichia coli ; little is known about how stringent signalling is regulated in species that live in consistently nutrient‐limited (i.e. oligotrophic) environments. Here we define the input logic and transcriptional output of the stringent response in the oligotroph, Caulobacter crescentus . The sole Rsh protein, SpoT CC , binds to and is regulated by the ribosome, and exhibits AND‐type control logic in which amino acid starvation is a necessary but insufficient signal for activation of ppGpp synthesis. While both glucose and ammonium starvation upregulate the synthesis of ppGpp, SpoT CC detects these starvation signals by two independent mechanisms. Although the logic of stringent response control in C. crescentus differs from E. coli , the global transcriptional effects of elevated ppGpp are similar, with the exception of 16S rRNA transcription, which is controlled independently of spoT CC . This study highlights how the regulatory logic controlling the stringent response may be adapted to the nutritional niche of a bacterial species.