Like MalE-SoxS , MarA ( i ) activated the transcription of zwf , fpr , fumC , micF , nfo , and sodA ; ( ii ) required a 21-bp '' soxbox '' sequence to activate zwf transcription ; and ( iii ) was '' ambidextrous , '' i. e. , required the C-terminal domain of the a subunit of RNA polymerase for activation of zwf but not fumC or micF .