ARSD1_ECOLX arsD 120 Inducer-independent trans-acting repressor of the ars operon. MKTLMVFDPAMCCSTGVCGTDVDQALVDFSTDVQWLKQCGVQIERFNLAQQPMSFVQNEKVKAFIEASGAEGLPLLLLDGETVMAGRYPKRAELARWFGIPLDKVGLAPSGCCGGNTSCC Arsenical resistance operon trans-acting repressor ArsD