Question

Under conditions of nutrient starvation, bacteria produce a protein that binds to the 3′ end of 16S rRNA. What is the result of this interaction and why is it beneficial to the cell?

Short answer

The production of ribosome modulation factor (RMF) and hibernation promoting factor (HPF) proteins during nutrient starvation binds to the 3’end of 16S rRNA and induces conformational changes in the 30S subunit, which leads to the production of inactive ribosomes. The formation of such ribosomes leads to a condition of ribosome hibernation that helps the cells survive stress.

Step-by-step solution

Nutrient Starvation

Nutrient starvation refers to a stress condition whenthe organism hasno nutrient supply and it must rely entirely on internal stores for growth. All organisms exhibit various responses to survive the condition of nutrient starvation. For instance, human burn fats to obtain energy. On the other hand, bacteria undergo physiological and morphological changes.

Bacteria response to nutrient starvation

During nutrient starvation, bacterial cell survival is aided by "ribosome hibernation," which is brought on by the expression of stationary-phase proteins such as ribosome modulation factor (RMF) and hibernation promoting factor (HPF).

The binding site of RMF overlaps with that of the messenger RNA (mRNA) Shine-Dalgarno sequence, preventing the interaction between the mRNA and the 16S ribosomal RNA. The binding of RMF and HPF to the ribosome induces a conformational change of the 30S head domain that promotes the formation of ribosomes into translationally inactive 100S dimers, thereby inhibiting protein synthesis.

When nutrients are few, bacteria slow down protein synthesis by forming 100S dimers, stop growing, and enter a stationary phase.