Question

Certain pathogens make fimbriae to attach to the cells lining the gut of their host animal. However, it would be a waste of resources to make fimbriae when not in the gut. In some bacteria, fibrial gene transcription is initiated when the cell detects leucine (L), which would likely be abundant in a nutrient-rich environment such as an intestine. The fimbriae (fim) genes are under positive control wherein a regulatory protein (FRP) binds to an activator binding site when leucine is present. RNA polymerase is shown here as RNAP. Which molecule is acting as an inducer Which molecule is acting as an activator? In which scenario (A or B) are the fim genes being transcribed?

Answer 1