Impact of Small RNA Sponges on Regulatory RNA Networks in Bacteria

Decades of research into the noncoding transcriptome have unveiled a complex, multilayered web of molecular interactions that govern gene expression, protein synthesis, and cellular function, challenging the once-presumed linear simplicity of the flow of genetic information. In bacteria, highly diverse small RNAs (sRNAs) play a crucial role in gene expression, often acting at the heart of large regulatory networks to modulate cellular processes through direct base-pairing interactions with target messenger RNAs (mRNAs). The expression of most sRNAs is tightly controlled at the level of transcription, but RNA sponges have recently emerged as an additional layer of regulation restricting sRNA activity and abundance. By titrating sRNAs and influencing their interactions with target mRNAs and RNA-binding proteins, RNA sponges contribute to the fine-tuning of global gene expression networks. In addition, the integration of RNA sponges into functional loops promotes elegant crosstalk between major regulons at the posttranscriptional level.