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R-loop induced stress response by second (p)ppGpp synthetase in Mycobacterium smegmatis: functional and domain interdependence

Krishnan, Sushma and Petchiappan, Anushya and Singh, Albel and Bhatt, Apoorva and Chatterji, Dipankar (2016) R-loop induced stress response by second (p)ppGpp synthetase in Mycobacterium smegmatis: functional and domain interdependence. In: MOLECULAR MICROBIOLOGY, 102 (1). pp. 168-182.

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Official URL: http://dx.doi.org/10.1111/mmi.13453


Persistent R-loops lead to replicative stress due to RNA polymerase stalling and DNA damage. RNase H enzymes facilitate the organisms to survive in the hostile condition by removing these R-loops. MS_RHII-RSD was previously identified to be the second (p)ppGpp synthetase in Mycobacterium smegmatis. The unique presence of an additional RNase HII domain raises an important question regarding the significance of this bifunctional protein. In this report, we demonstrate its ability to hydrolyze R-loops in Escherichia coli exposed to UV stress. MS_RHII-RSD gene expression was upregulated under UV stress, and this gene deleted strain showed increased R-loop accumulation as compared to the wild type. The domains in isolation are known to be inactive, and the full length protein is required for its function. Domain interdependence studies using active site mutants reveal the necessity of a hexamer form with high alpha helical content. In previous studies, bacterial RNase type HI has been mainly implicated in R-loop hydrolysis, but in this study, the RNase HII domain containing protein showed the activity. The prospective of this differential RNase HII activity is discussed. This is the first report to implicate a (p)ppGpp synthetase protein in R-loop-induced stress response.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the WILEY-BLACKWELL, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 03 Dec 2016 06:05
Last Modified: 03 Dec 2016 06:05
URI: http://eprints.iisc.ac.in/id/eprint/55244

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