DqsIR quorum sensing-mediated gene regulation of the extremophilic bacteriumDeinococcus radioduransin response to oxidative stress

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Abstract

Summary

Here, we show that AHLs can be employed byDeinococcus radiodurans, which belongs to the unique phylumDeinococcus-Thermusand is known for its cellular resistance to environmental stresses. An AHL-mediated quorum-sensing system (DqsI/DqsR) was identified inD. radiodurans. We found that under non-stress conditions, the AHL level was “shielded” by quorum quenching enzymes, whereas AHLs accumulated whenD. radioduranswas exposed to oxidative stress. Upon exposure to H2O2, AHL synthetic enzymes (DqsI) were immediately induced, while the expression of quorum-quenching enzymes began to increase approximately 30 min after exposure to H2O2, as shown by time-course analyses of gene expression. BothdqsImutant (DMDqsI) anddqsRmutant (MDqsR) were more sensitive to oxidative stress compared with the wild-type strain. Exogenous AHLs (5 μM) could completely restore the survival fraction of DMDqsI under oxidative stress. RNA-seq analysis showed that a number of genes involved in stress-response, cellular cleansing, and DNA repair had altered transcriptional levels in MDqsR. The DqsR, acting as a regulator of quorum sensing, controls gene expression along with AHLs. Hence, the DqsIR-mediated quorum sensing that mediates gene regulation is an adaptive strategy forD. radioduransin response to oxidative stresses and is conserved in the extremophilicDeinococcusbacteria.

We identified an AHL-mediated quorum-sensing system (DqsI/DqsR) in Deinococcus radiodurans, which belongs to the unique phylum Deinococcus-Thermus. The AHL level, which was restrained by AHL-quenching enzymes, was accumulated via induction of AHL synthetic enzymes (DqsI) upon exposure to oxidative stress. The DqsR, acting as a regulator of quorum sensing, controlled gene expression along with AHLs. The DqsIR quorum sensing is an adaptive strategy for D. radiodurans in response to oxidative stresses.

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