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The role of -subunit of Escherichia coli RNA polymerase in stress response

Bhardwaj, Neerupma and Syal, Kirtimaan and Chatterji, Dipankar (2018) The role of -subunit of Escherichia coli RNA polymerase in stress response. In: GENES TO CELLS, 23 (5). pp. 357-369.

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Official URL: http://dx.doi.org/ 10.1111/gtc.12577


ppGpp, an alarmone for stringent response, plays an important role in the reprogramming of the transcription complex at the time of stress. In Escherichia coli, ppGpp mediates its action by binding to at least two different sites on RNA polymerase (RNAP). One of the sites to which ppGpp binds to RNAP is at the - interface; however, the underlying molecular mechanism and the physiological relevance of ppGpp binding to this site remain unclear. In this study, we have performed UV cross-linking experiments using P-32 azido-labeled ppGpp to probe its association with RNAP in the absence and presence of , and observed weaker binding of ppGpp to the RNAP without . Furthermore, we followed the binding kinetics of ppGpp to RNAP with and without by isothermal titration calorimetry and found it to be concurrent with the cross-linking results. Native is intrinsically disordered, and we have used a previously characterized structured mutant of , which affects the plasticity of the active site of RNAP. Results show that the flexibility conferred by the unstructured is a prerequisite for ppGpp binding to RNAP. We have analyzed the stress-associated phenotypes in an E.coli strain devoid of (rpoZ). ppGpp levels in rpoZ strain were found to be similar to that of the wild-type strain. Interestingly, when the rpoZ strain of E.coli was transferred after nutritional stress to an enriched media, the recovery of growth was compromised. We have identified a new phenotype of rpoZ strain corresponding to defect in biofilm formation in minimal media.

Item Type: Journal Article
Additional Information: Copy right for this article belong to WILEY, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Depositing User: Id for Latest eprints
Date Deposited: 23 May 2018 14:55
Last Modified: 23 May 2018 14:55
URI: http://eprints.iisc.ac.in/id/eprint/59919

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