Abstract
The Escherichia coli eukaryote-like serine/threonine kinase, encoded by yeaG, is expressed in response to diverse stresses, including nitrogen (N) starvation. A role for yeaG in bacterial stress response is unknown. Here we reveal for the first time that wild-type E. coli displays metabolic heterogeneity following sustained periods of N starvation, with the metabolically active population displaying compromised viability. In contrast, such heterogeneity in metabolic activity is not observed in an E. coli ∆yeaG mutant, which continues to exist as a single and metabolically active population and thus displays an overall compromised ability to survive sustained periods of N starvation. The mechanism by which yeaG acts, involves the transcriptional repression of two toxin/antitoxin modules, mqsR/mqsA and dinJ/yafQ. This, consequently, has a positive effect on the expression of rpoS, the master regulator of the general bacterial stress response. Overall, results indicate that yeaG is required to fully execute the rpoS-dependent gene expression program to allow E. coli to adapt to sustained N starvation and unravels a novel facet to the regulatory basis that underpins adaptive response to N stress.
Highlights
Revealed that the expression of yeaG and yeaH are highly upregulated in E. coli in response to diverse stresses, including low pH, hyperosmotic conditions, entry into stationary phase and sulphur limitation[5,6]
We focused on the biology of mqsR/mqsA and dinJ/yafQ to decipher how both of these TA modules could contribute to the properties of the ∆yeaG mutant strain: The mqsR/mqsA TA module is linked to regulation of the general stress response because it directly represses the transcription of rpoS, which encodes for σ 38, the RNA polymerase associated σ factor that is responsible for executing the general bacterial stress response, and cspD, which encodes for the cold-shock protein D, a DNA replication inhibitor[18,19]
It is well established that rpoS is not expressed in exponentially growing bacteria and the regulation of its expression is tightly controlled at the transcription, translation and protein stability and activity levels as it impacts multiple physiological properties of the cell that affect growth
Summary
Revealed that the expression of yeaG and yeaH are highly upregulated in E. coli in response to diverse stresses, including low pH, hyperosmotic conditions, entry into stationary phase and sulphur limitation[5,6]. ESTKs have emerged as critical components of bacterial signal transduction systems and are central to important and diverse cellular functions, including bacterial stress response[8,9]. Consistent with their different biological roles, many eSTKs are modular and display a high diversity in domain organization[10]. AAA+ domain-containing proteins are oligomeric mechanochemical enzymes that transform chemical energy derived from ATP binding and hydrolysis into mechanical force to induce conformational changes in their substrates[12] It seems that YeaG is an atypical, yet highly conserved, eSTK. We have investigated the role of E. coli YeaG in the adaptive response to N starvation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
