AUTHOR=Xue Dong , Chen Yun , Li Jiang , Han Jiahui , Liu Yingying , Jiang Shijie , Zhou Zhengfu , Zhang Wei , Chen Ming , Lin Min , Ongena Marc , Wang Jin 

TITLE=Targeting Hsp20 Using the Novel Small Non-coding RNA DnrH Regulates Heat Tolerance in Deinococcus radiodurans

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.02354

DOI=10.3389/fmicb.2019.02354

ISSN=1664-302X

ABSTRACT=<p>Small non-coding RNAs (ncRNAs) are a class of regulatory molecules, which remain understudied in bacteria. In the extremophilic bacterium <italic>Deinococcus radiodurans</italic>, although hundreds of ncRNAs have been identified, few have been characterized in detail. In this study, we report the identification and characterization of a novel heat-inducible ncRNA named <italic>DnrH</italic>. Heat tolerance analysis showed that deleting <italic>DnrH</italic> significantly inhibited viability in response to high temperature conditions. Comparative phenotypic and qRT-PCR analyses of a <italic>DnrH</italic> mutant (Δ<italic>DnrH</italic>) and wild-type (WT) <italic>D. radiodurans</italic> suggested that <italic>DnrH</italic> is potentially involved in regulating the expression of the heat shock-related gene <italic>Hsp20</italic>. Microscale thermophoresis and genetic complementation showed that a 28-nucleotide (nt) sequence in the stem-loop structure of <italic>DnrH</italic> (143–170 nt) pairs with its counterpart in the coding region of <italic>Hsp20</italic> mRNA (91–117 nt) via a 22 nt region. <italic>In vivo</italic>, mutation of the 22-nt region in the <italic>D. radiodurans</italic> genome led to a reduction in heat tolerance similar to that observed in the <italic>DnrH</italic>-mutant. Our results show that <italic>DnrH</italic> positively influences heat tolerance by increasing the transcription of <italic>Hsp20</italic> mRNA, demonstrating, for the first time, a ncRNA that directly controls the expression of a heat stress-resistance gene. This work provides new insight into the heat stress response mechanism of <italic>D. radiodurans</italic> as well as other extremophiles that express similar Hsp20 proteins.</p>