Gene Expression of Nitrogenase Through NtrC is Downregulated in High

Question

Gene expression of nitrogenase through NtrC is downregulated in high concentrations of
A) carbon dioxide.
B) nitrogen.
C) nitrate.
D) ammonium.
E) FeMo protein.

Accepted Answer

Ammonium is a readily available source of nitrogen for bacteria, so when present in high concentrations, the cells stop producing nitrogenase, which is an energetically expensive process. NtrC is a transcriptional activator that promotes the transcription of genes involved in nitrogen metabolism, including nitrogenase. When nitrogen is available in the form of ammonium, NtrC is no longer needed, and the expression of nitrogenase is downregulated.