The araC gene is associated with the arabinose operon in bacteria, such as E. coli. For the araC gene to be activated, the presence of arabinose is crucial. AraC is a regulatory protein that can act as both an activator and a repressor, depending on the presence or absence of arabinose.
In the absence of arabinose, AraC represses the ara operon. When arabinose is present, it binds to AraC, causing a conformational change in the protein. This altered form of AraC then acts as an activator, promoting the transcription of genes in the ara operon.
So, in summary, arabinose is the key inducer required to activate the araC gene and initiate the expression of genes in the arabinose operon.