16 Questions
What is the primary function of stem-loops in mRNA secondary structure?
To create a stable, double-stranded region with a loop at the end
What is the role of RNA-binding proteins in regulating gene expression?
To alter riboswitch conformation, affecting gene expression
What is the basis for classifying riboswitches into different categories?
The ligand specificity, secondary structure, and gene regulation of the riboswitch
What is the outcome of ligand binding to a riboswitch?
The riboswitch undergoes a conformational change, affecting gene expression
What is the role of riboswitches in regulating translation initiation?
To control the accessibility of the ribosome binding site
What is the function of an ON switch riboswitch?
To allow translation initiation when bound to a ligand
What happens when Rho reaches the terminator in a normal situation?
It blocks RNA polymerase and prevents transcription.
What is the function of TRAP protein in the Trp operon?
It prevents the formation of terminator structures.
What happens when there is a low concentration of Trp?
TRAP protein is inactivated and transcription continues.
What is the function of anti-TRAP protein?
It prevents the formation of terminator structures.
What is the signal that triggers the formation of anti-TRAP protein?
The absence of Trp.
What is the role of tRNA in the formation of anti-TRAP protein?
It signals the formation of anti-TRAP protein.
What is the difference between the Trp operon in E. coli and B. subtilis?
The Trp operon in B. subtilis is regulated by the TRAP protein.
What is a common characteristic of the three mechanisms of attenuation?
They all form terminator structures.
What is the significance of the study on different bacteria?
It indicates that different bacteria prefer different mechanisms of attenuation.
What is the function of the ribosome in the mechanism of attenuation in E. coli?
It is stuck and prevents the Rho factor from reaching the terminator.
Study Notes
MRNA Secondary Structure
- Riboswitches are regions of mRNA that can adopt specific secondary structures
- These structures are critical for riboswitch function and can be altered by binding of small molecules
- Secondary structures can be:
- Stem-loops: stable, double-stranded regions with a loop at the end
- Pseudoknots: regions where the RNA strand folds back on itself, forming a knot-like structure
- Junctions: regions where multiple stem-loops meet
RNA-binding Proteins
- RNA-binding proteins can interact with riboswitches to regulate gene expression
- These proteins can:
- Bind specifically to riboswitch secondary structures
- Alter riboswitch conformation, affecting gene expression
- Act as co-factors to enhance or inhibit riboswitch function
Riboswitch Classification
- Riboswitches can be classified into several categories based on:
- Ligand specificity: e.g., purine, thiamine, or flavin mononucleotide (FMN) binding
- Secondary structure: e.g., stem-loop, pseudoknot, or junction
- Gene regulation: e.g., transcriptional or translational control
- Bacterial or archaeal origin: e.g., TPW, TPP, or FMN riboswitches
RNA-ligand Interactions
- Riboswitches recognize and bind specific small molecules (ligands) to regulate gene expression
- Ligand binding can:
- Induce conformational changes in the riboswitch, affecting gene expression
- Alter the accessibility of the ribosome binding site
- Inhibit or activate translation initiation
Translation Initiation
- Riboswitches can regulate translation initiation by controlling:
- Ribosome binding site (RBS) accessibility
- Initiation codon recognition
- Translation initiation complex formation
- Riboswitches can act as:
- ON switches: allowing translation initiation when bound to a ligand
- OFF switches: inhibiting translation initiation when bound to a ligand
This quiz covers the structure and function of riboswitches, including their secondary structures, binding of small molecules, and regulation of gene expression. It also explores the classification of riboswitches and their role in translation initiation.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
