Question

Overexpression of rate-limiting enzymes leads to

• A. Reduced flux
• B. Increased pathway flux
• C. Cell death
• D. Gene deletion

Hint:

Remember: \[ \boxed{\text{Rate-Limiting Enzyme} = \text{Metabolic Bottleneck}} \] Increasing its expression generally increases the overall metabolic pathway flux.

Answer 1

The Correct Option is B

Concept: A rate-limiting enzyme catalyzes the slowest step of a metabolic pathway and therefore determines the overall rate (flux) of the pathway. In metabolic engineering, increasing the expression of this enzyme often enhances the flow of metabolites toward the desired product.

Step 1: Understand pathway flux.
Metabolic flux refers to the rate at which substrates move through a metabolic pathway. \[ \boxed{\text{Higher Enzyme Activity} \Longrightarrow \text{Higher Metabolic Flux}} \] If the slowest step is accelerated, the overall pathway becomes faster.

Step 2: Importance of overexpression.
Overexpressing a rate-limiting enzyme can:
• Increase product formation.
• Improve industrial fermentation yield.
• Reduce metabolic bottlenecks.
• Enhance biosynthetic efficiency.

Step 3: Eliminate incorrect options.

• Reduced flux is opposite to the expected effect.
• Cell death is not a direct consequence.
• Gene deletion removes enzyme activity instead of increasing it.
• Hence, pathway flux increases. Final Answer: \[ \boxed{Option (B) is correct \]