Riboregulation

Riboregulation refers to the regulation of gene expression by RNA molecules and RNA structures rather than by proteins. It encompasses regulatory elements embedded in RNA that respond to metabolites, temperature, or other signals, as well as RNA–protein complexes that modulate RNA function. Riboregulation can act at transcriptional, post-transcriptional, and translational levels, allowing rapid and reversible control of gene expression.

In bacteria and archaea, common riboregulators include riboswitches in the 5' untranslated region that bind small molecules to change RNA conformation, influencing transcription termination or translation initiation. Small regulatory RNAs (sRNAs) pair with target mRNAs to alter stability or ribosome access, often with help from chaperone proteins such as Hfq. Ribozymes are catalytic RNAs that can self-cleave or modify other RNAs, affecting gene expression. RNA thermometers alter secondary structure in response to temperature changes, controlling translation initiation and thereby adjusting protein production to environmental conditions.

In eukaryotes, RNA-based regulation includes microRNAs and small interfering RNAs that guide Argonaute-containing complexes to mRNA targets, causing translational repression or decay. The RNA interference pathway represents a central mechanism of riboregulation in many animal and plant systems, linking small RNA pathways to gene silencing.

In synthetic biology, engineered riboregulators such as toehold switches enable programmable control of gene expression through designed RNA interactions. Research in this area aims to improve predictability, reduce off-target effects, and integrate RNA-based control into larger regulatory networks.