What is riboswitch in biology?

In molecular biology, a riboswitch is a regulatory segment of a messenger RNA molecule that binds a small molecule, resulting in a change in production of the proteins encoded by the mRNA. The original definition of the term “riboswitch” specified that they directly sense small-molecule metabolite concentrations.

What do riboswitches regulate?

These regulatory elements are known as riboswitches and are defined as mRNA elements that bind metabolites or metal ions as ligands and regulate mRNA expression by forming alternative structures in response to this ligand binding (Figure 1; Nudler & Mironov 2004; Tucker & Breaker 2005; Winkler 2005).

What is the function of a riboswitch?

Riboswitches are structured mRNA elements involved in gene regulation that respond to the intracellular concentration of specific small molecules. Binding of their cognate ligand is thought to elicit a global conformational change of the riboswitch, in addition to modulating the fine structure of the binding site.

Is riboswitch a Microrna?

An analog of the riboswitch, the protein-directed RNA switch (PDRS), has been identified as an important regulatory mechanism of gene expression in mammalian cells. RNA-binding proteins and microRNAs are two major executors of PDRS via their interaction with target transcripts in mammals.

What does the 5 UTR do?

The 5′ untranslated region (5′ UTR) (also known as a leader sequence, transcript leader, or leader RNA) is the region of an mRNA that is directly upstream from the initiation codon. This region is important for the regulation of translation of a transcript by differing mechanisms in viruses, prokaryotes and eukaryotes.

How do you detect riboswitch?

To detect a riboswitch, the input is first scanned for the motif sequence(s), and then the optimal secondary structure is predicted. If the predicted structure matches the known structure of the riboswitch, it may be considered a putative riboswitch.

Do Riboswitches exist in eukaryotes?

Riboswitches can be regarded as a regulatory mechanism for gene expression, and are involved in bacterial RNA networks. Riboswitches have also been seen in the 3′-UTRs of eukaryotic genes, for example the thiamine pyrophosphate (TPP) riboswitch in the THIC gene in plants.

What is an example of a riboswitch?

Examples of riboswitch ligands include glycine, coenzyme B12, thiamine, flavin mononucleotides, S-adenosylmethionine, and guanine. As such, riboswitches represent unique target opportunities for drugs.

How many human miRNAs are there?

There are now over 2000 miRNAs that have been discovered in humans and it is believed that they collectively regulate one third of the genes in the genome. miRNAs have been linked to many human diseases and are being pursued as clinical diagnostics and as therapeutic targets.

How does siRNA silence gene expression?

The siRNA-induced post transcriptional gene silencing starts with the assembly of the RNA-induced silencing complex (RISC). The complex silences certain gene expression by cleaving the mRNA molecules coding the target genes. This cleavage results in mRNA fragments that are further degraded by cellular exonucleases.

Are UTR exons?

Of course, UTRs ARE parts of exons. Usually of the first and the terminal exons for the 5′ and 3′ UTRs respectively, but not only.

What is the function of 3 UTR?

3′ untranslated regions (3′ UTRs) of messenger RNAs (mRNAs) are best known to regulate mRNA-based processes, such as mRNA localization, mRNA stability, and translation.

How are cyclic di-GMP riboswitches related to each other?

cyclic di-GMP riboswitches bind the signaling molecule cyclic di-GMP in order to regulate a variety of genes controlled by this second messenger. Two classes of cyclic di-GMP riboswitches are known: cyclic di-GMP-I riboswitches and cyclic di-GMP-II riboswitches. These classes do not appear to be structurally related.

How many riboswitches are there in the world?

Riboswitches specifically recognize various ligands such as coenzymes, ions, amino acids, nucleotides (and derivatives) and signaling molecules [ 11, 16 ]. Currently, there are at least 38 validated riboswitch classes that include more than 100,000 riboswitch representatives [ 16 ].

How are riboswitches related to the expression platform?

Riboswitches are often conceptually divided into two parts: an aptamer and an expression platform. The aptamer directly binds the small molecule, and the expression platform undergoes structural changes in response to the changes in the aptamer.

How does the t.tengcongenesis ydaO riboswitch work?

The T. tengcongenesis ydaO riboswitch, like its B. subtilis counterpart, likely functions through a transcription termination mechanism, with the c-di-AMP bound state representing an ‘off’ switch. Ren, A. and Patel, D. J. (2014). c-di-AMP binds the ydaO riboswitch in two pseudo-symmetry-related pockets.