Petchiappan, A and Naik, SY and Chatterji, D (2020) RelZ-mediated stress response in mycobacterium smegmatis: PGPP synthesis and its regulation. In: Journal of Bacteriology, 202 (2).
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Abstract
Stringent response is a conserved stress response mechanism in which bacteria employ the second messengers guanosine tetraphosphate and guanosine pentaphosphate collectively termed (p)ppGpp to reprogram their cellular processes under stress. In mycobacteria, these alarmones govern a multitude of cellular phenotypes, such as cell division, biofilm formation, antibiotic tolerance, and long-term survival. Mycobacterium smegmatis possesses the bifunctional RelMsm as a (p)ppGpp synthetase and hydrolase. In addition, it contains a short alarmone synthetase MS_RHII-RSD (renamed RelZ), which contains an RNase H domain in tandem with the (p)ppGpp synthetase domain. The physiological functions of RelMsm have been well documented, but there is no clear picture about the cellular functions of RelZ in M. smegmatis. RelZ has been implicated in R-loop induced stress response due to its unique domain architecture. In this study, we elucidate the differential substrate utilization pattern of RelZ compared to that of RelMsm. We unveil the ability of RelZ to use GMP as a substrate to synthesize pGpp, thereby expanding the repertoire of second messengers known in mycobacteria. We have demonstrated that the pGpp synthesis activity of RelZ is negatively regulated by RNA and pppGpp. Furthermore, we investigated its role in biofilm formation and antibiotic tolerance. Our findings highlight the complex role played by the RelZ in cellular physiology of M. smegmatis and sheds light upon its functions distinct from those of RelMsm. IMPORTANCE Bacteria utilize nucleotide messengers to survive the hostile environmental conditions and the onslaught of attacks within the host. The second messengers guanosine tetraphosphate and pentaphosphate (p)ppGpp have a profound impact on the long-term survival, biofilm formation, antibiotic tolerance, virulence, and pathogenesis of bacteria. Therefore, understanding the stress response mechanism regulated by (p)ppGpp is essential for discovering inhibitors of stress response and potential drug targets. Mycobacterium smegmatis contains two (p)ppGpp synthetases: RelMsm and RelZ. Our study unravels the novel regulatory mechanisms of RelZ activity and its role in mediating antibiotic tolerance. We further reveal its ability to synthesize novel second messenger pGpp, which may have regulatory roles in mycobacteria. Copyright © 2020 American Society for Microbiology. All Rights Reserved.
| Item Type: | Journal Article |
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| Publication: | Journal of Bacteriology |
| Publisher: | American Society for Microbiology |
| Additional Information: | The copyright for this article belongs to the Authors. |
| Keywords: | bacterial protein; double stranded DNA; guanosine 3' diphosphate 5' diphosphate; guanosine 3' diphosphate 5' triphosphate; guanosine diphosphate; guanosine phosphate; guanosine triphosphate; reiz protein; single stranded RNA; unclassified drug; antiinfective agent; bacterial protein; guanine nucleotide; guanosine 3' diphosphate 5' diphosphate, alkaline hydrolysis; Article; bacterial virulence; cell division; cell function; cell surface; comparative study; controlled study; DNA RNA hybridization; enzyme specificity; fluorescence; long term survival; mass spectrometry; Mycobacterium smegmatis; Mycobacterium tuberculosis; negative feedback; nonhuman; phenotype; priority journal; protein secondary structure; regulatory mechanism; second messenger; sequence alignment; synthesis; thin layer chromatography; biofilm; drug effect; gene expression regulation; genetics; metabolism; Mycobacterium smegmatis; physiology; promoter region, Anti-Bacterial Agents; Bacterial Proteins; Biofilms; Gene Expression Regulation, Bacterial; Guanine Nucleotides; Guanosine Tetraphosphate; Mycobacterium smegmatis; Promoter Regions, Genetic |
| Department/Centre: | Division of Biological Sciences > Molecular Biophysics Unit |
| Date Deposited: | 24 Jan 2023 05:01 |
| Last Modified: | 24 Jan 2023 05:01 |
| URI: | https://eprints.iisc.ac.in/id/eprint/79320 |
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