Transcription factor that regulates the expression of several genes involved in the transport and metabolism of L-arabinose (PubMed:4362626, PubMed:328165, PubMed:6251457, PubMed:2962192, PubMed:6319708, PubMed:2231717, PubMed:1447222). Functions both as a positive and a negative regulator (PubMed:328165, PubMed:6251457). In the presence of arabinose, activates the expression of the araBAD, araE, araFGH and araJ promoters (PubMed:4362626, PubMed:328165, PubMed:6251457, PubMed:2962192, PubMed:6319708, PubMed:2231717, PubMed:1447222). In the absence of arabinose, negatively regulates the araBAD operon (PubMed:6251457). Represses its own transcription (PubMed:328165). Acts by binding directly to DNA (PubMed:4943786, PubMed:6251457, PubMed:2962192, PubMed:2531226, PubMed:1447222). Arabinose converts the repressor form of AraC to the activator form to regulate the araBAD promoter (PubMed:2962192, PubMed:3279415). In the absence of arabinose, AraC binds to the araO2 and araI1 half-sites in the promoter region of the araBAD operon, leading to the formation of a DNA loop that blocks access of RNA polymerase to the promoter. In the presence of arabinose and the cyclic AMP receptor protein (CRP), it binds to the adjacent half-sites araI1 and araI2, leading to the binding of RNA polymerase to the promoter region and transcription of the araBAD operon (PubMed:2962192, PubMed:3279415). AraI1 acts as a switch mechanism allowing both the repressor and the activator forms of AraC protein to regulate the araBAD promoter (PubMed:2962192, PubMed:3279415). Inhibited by D-fucose, which binds competitively to the same site on the protein (PubMed:9367758). Homodimer. Negatively autoregulated (PubMed:328165, PubMed:6377308, PubMed:3279415). Autoregulation is either greatly reduced or nonexistent immediately after the addition of L-arabinose (PubMed:6377308). Transcription is stimulated by CRP in the presence of cAMP (PubMed:328165, PubMed:6377308). Contains an N-terminal domain that binds arabinose and mediates dimerization, an inter-domain linker region, and a C-terminal domain that binds DNA (PubMed:9103202, PubMed:9367758, PubMed:26800223). Arabinose is bound within a beta barrel and is completely buried by the N-terminal arm of the protein (PubMed:9103202). The DNA-binding domain contains seven helices arranged in two semi-independent subdomains, each containing one helix-turn-helix DNA binding motif, joined by a 19 residue central helix (PubMed:19422057).