Question

Which one of the following metabolites is associated with bacterial stringent response?

• A. Cyclic di-GMP (CDG)
• B. Guanosine tetraphosphate (ppGpp)
• C. Cyclic-AMP (cAMP)
• D. Cyclic-GMP (cGMP)

Hint:

The stringent response is triggered by nutrient deprivation in bacteria, and ppGpp is the critical metabolite involved in this response, adjusting bacterial metabolism to stress conditions.

Answer 1

The Correct Option is B

The bacterial stringent response is a stress response mechanism in bacteria that is triggered by nutrient deprivation, particularly amino acid starvation. The key metabolites associated with this response are guanosine tetraphosphate (ppGpp) and guanosine diphosphate (pGpp). These molecules act as signaling molecules that help the bacteria adjust their metabolic processes in response to stress. The accumulation of ppGpp reduces the expression of rRNA and tRNA, thus slowing down ribosome synthesis and redirecting resources to essential survival processes. Hence, statement (B) is correct.
- (A): Cyclic di-GMP (CDG) is primarily involved in regulating biofilm formation and motility in bacteria, but not directly related to the stringent response. Therefore, statement (A) is incorrect.
- (C): Cyclic-AMP (cAMP) is involved in bacterial signaling but is not the key player in the stringent response, making statement (C) incorrect.
- (D): Cyclic-GMP (cGMP) is a signaling molecule in eukaryotes and not directly associated with the bacterial stringent response. Hence, statement (D) is incorrect.
Thus, the correct answer is (B).