In the absence-of-arabinose , AraC represses transcription of araBAD by forming a repression loop .
Although arabinose-dependent repression by AraC has not been observed before , there are clear parallels with arabinose-de-pendent activation of araBAD transcription .
Thus , arabinose-dependent repression of ydeNM by AraC would use the same mechanism as arabinose-dependent activation of araBAD .