Question

How can the action of regulatory transcription factors be modulated (there are three ways)?

Answer 1

The action of regulatory transcription factors can be modulated in three ways. They are as follows

• Protein- Protein interactions
• Binding of an effector molecule
• Covalent modifications.

Protein- protein interactions : Two or more protein molecules combine through physical interactions that has high specificity to form protein- protein interaction. This can occur through hydrogen bonding, hydrophobic effect and electrostatic forces. There are some DNA sequences that enhance the protein - protein interactions in the transcription factors. This enhancement helps them to work effectively. Hence the action of regulatory transcription factors can be modulated.

Binding of an effector molecule : Some proteins or molecules bind with the DNA to effect the transcription. They can increase or decrease the rate of transcription buy modulating the transcription factors. For example, the binding of lac repressor gene to the lac operon is decreased by the lactose thereby increasing the rate of reaction.

Covalent modifications : Covalent modification of regulatory transcription factors can modulate their action. In many processes such as DNA repair, DNA replication, transcription etc, the regulation of DNA accessibility is done by the covalent histone modification. Covalent histone modification modulates the chromatin inorder to regulate the DNA accessibility during those processes.