Summary
RNA elements that bind small metabolites and change structure to regulate gene expression directly.
In depth
Located in the 5' UTR of bacterial mRNAs, a riboswitch has an aptamer domain that binds a ligand (such as thiamine pyrophosphate or adenine) and an expression platform that changes folding, usually terminating transcription or blocking the ribosome binding site.
They need no protein and are drug targets.
Riboswitches respond to cofactors, amino acids, nucleobases and ions and show how RNA alone can sense metabolites and control genes without proteins. A ligand-bound aptamer changes the structure of the expression platform to form a terminator hairpin (stopping transcription) or hide the ribosome-binding site (blocking translation). Over 40 classes are known, and a few occur in plants and fungi.
They are potential antibiotic targets since they are common in bacteria and absent in humans; the compound roseoflavin, produced by a bacterium, binds the flavin mononucleotide riboswitch. They also support the RNA world hypothesis as likely ancient regulatory elements.
Example: the thiamine pyrophosphate riboswitch shuts off thiamine synthesis genes when the vitamin is plentiful.
Frequently asked questions
What is Riboswitches?
RNA elements that bind small metabolites and change structure to regulate gene expression directly.
Which area of biology covers Riboswitches, and how advanced is it?
Riboswitches is one of the 52 topics in Molecular Biology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Trp Operon, Transcription, Transcription Factors.
Can you give an example of Riboswitches?
The TPP riboswitch is found in all three domains of life.
What should I learn before Riboswitches?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to Riboswitches. Advanced topics assume the Intermediate vocabulary.
What topics are related to Riboswitches?
The closest topics to Riboswitches are Trp Operon, Transcription, Transcription Factors, Initiation, Elongation, Termination. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Riboswitches?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Riboswitches. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is Riboswitches different from Trp Operon?
Riboswitches: RNA elements that bind small metabolites and change structure to regulate gene expression directly. Trp Operon: A repressible operon turned off when tryptophan accumulates and activates the repressor. Read both side by side and note what each one explains.
How should I study Riboswitches step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Trp Operon and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.