Targeting Hsp20 Using the Novel Small Non-coding RNA Regulates Heat Tolerance in .

Small non-coding RNAs (ncRNAs) are a class of regulatory molecules, which remain understudied in bacteria. In the extremophilic bacterium , 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 . Heat tolerance analysis showed that deleting significantly inhibited viability in response to high temperature conditions. Comparative phenotypic and qRT-PCR analyses of a mutant (Δ) and wild-type (WT) suggested that is potentially involved in regulating the expression of the heat shock-related gene . Microscale thermophoresis and genetic complementation showed that a 28-nucleotide (nt) sequence in the stem-loop structure of (143-170 nt) pairs with its counterpart in the coding region of mRNA (91-117 nt) via a 22 nt region. , mutation of the 22-nt region in the genome led to a reduction in heat tolerance similar to that observed in the -mutant. Our results show that positively influences heat tolerance by increasing the transcription of 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 as well as other extremophiles that express similar Hsp20 proteins.