AUTHOR=Li Zhou , Zhu Li , Yu Zhaoqing , Liu Lu , Chou Shan-Ho , Wang Jieping , He Jin 

TITLE=6S-1 RNA Contributes to Sporulation and Parasporal Crystal Formation in Bacillus thuringiensis

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.604458

DOI=10.3389/fmicb.2020.604458

ISSN=1664-302X

ABSTRACT=<p>6S RNA is a kind of high-abundance non-coding RNA that globally regulates bacterial transcription by interacting with RNA polymerase holoenzyme. Through bioinformatics analysis, we found that there are two tandem 6S RNA-encoding genes in the genomes of <italic>Bacillus cereus</italic> group bacteria. Using <italic>Bacillus thuringiensis</italic> BMB171 as the starting strain, we have explored the physiological functions of 6S RNAs, and found that the genes <italic>ssrSA</italic> and <italic>ssrSB</italic> encoding 6S-1 and 6S-2 RNAs were located in the same operon and are co-transcribed as a precursor that might be processed by specific ribonucleases to form mature 6S-1 and 6S-2 RNAs. We also constructed two single-gene deletion mutant strains Δ<italic>ssrSA</italic> and Δ<italic>ssrSB</italic> and a double-gene deletion mutant strain Δ<italic>ssrSAB</italic> by means of the markerless gene knockout method. Our data show that deletion of 6S-1 RNA inhibited the growth of <italic>B. thuringiensis</italic> in the stationary phase, leading to lysis of some bacterial cells. Furthermore, deletion of 6S-1 RNA also significantly reduced the spore number and parasporal crystal content. Our work reveals that <italic>B. thuringiensis</italic> 6S RNA played an important regulatory role in ensuring the sporulation and parasporal crystal formation.</p>