Describe the mechanism by which the riboswitch in the E. coli thiM gene controls translation.

Name: Problem 26, Chapter 17: Molecular Biology
Uploaded: 2023-03-09T00:25:39-08:00
Duration: 4 min 27 s
Channel: Jennifer Stoner
Description: Describe the mechanism by which the riboswitch in the E. coli thiM gene controls translation.

step 1 When Tritofan is scarce, the entire 6 ,720 nucleotide polycystronic TRP MRNA, including the TRPL

Describe the mechanism by which the riboswitch in the E....

Key Concepts

Riboswitch

A riboswitch is a regulatory segment within an mRNA molecule that binds specific metabolites or small molecules. This binding event causes a change in the mRNA’s structure which then influences gene expression, making riboswitches critical in the regulation of genes in response to cellular metabolite levels.

RNA Secondary Structure

The functionality of riboswitches relies on changes in the RNA secondary structure. Upon ligand binding, the mRNA rearranges its hairpins and loops, which can either expose or hide critical sequences such as the ribosome binding site, thereby modulating the gene's expression.

Translation Regulation

Translation regulation by riboswitches occurs when structural changes in the mRNA affect the accessibility of the ribosome binding site. If the binding site is sequestered due to a conformational change, the ribosome cannot bind, and translation is inhibited; conversely, exposing the site promotes translation.

Ligand Binding Induced Conformational Change

The binding of a specific ligand to the riboswitch results in a conformational change in the mRNA structure. This structural switch is the key to controlling the downstream expression of the gene, as it directly affects the process of translation by altering ribosome access.

Feedback Regulation in Gene Expression

Riboswitches often act within a feedback loop that monitors and adjusts the levels of a specific metabolite within the cell. By controlling the expression of genes related to metabolite synthesis or transport, riboswitches help maintain metabolic balance and homeostasis.

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