(a-b) Consensus sequence for putative Xre binding motifs in I-F3a and I-Fb elements.
(c-d) Xre-binding resolved by EMSA. DNA fragments with the transcription control regions were incubated with increasing amounts of Xre protein from the respective element before electrophoresis (100 nM DNA; protein:DNA ratios = 0,2,5,10,20:1). (e-f) Promoter function resolved by LacZ expression monitored by Miller units at various arabinose controlled Xre expression levels. Transcription control regions are indicated from V. cholerae HE-45 Tn6677 (Vc), V. parahaemolyticus RIMD221063 (Vp). A. salmonicida S44 Tn6900 (As), and Vibrio sp. 10N.286.45.B6 (VB6).