DNA looping in ara operon causes
DNA looping in ara operon results from simultaneous binding of AraC dimer to distantly separated operator half-sites, bringing them into close physical proximity through protein-mediated bending. Looped complex imposes severe steric block on RNA polymerase binding site, prevents formation of transcription bubble, and constrains promoter DNA topology in configuration unfavorable for activation. This mechanical hindrance efficiently silences araBAD transcription in absence of inducing sugar, more effective than simple occupancy of single operator site, analogous to LacI repressor tetramer loopin
Ref: Wikipedia L-arabinose operon – DNA looping between AraC bound at araI and araO2 blocks RNA polymerase and causes repression.