Binding of purified Irr to the promoter of <i>mbfA</i> and <i>ccpA</i> as determined by Electrophoretic Mobility Shift Assays.

<p>(A) Binding of Irr to the promoter region of <i>mbfA</i> (180 bp). All reactions contain the same amount of ³²P end-labeled DNA fragment (3.08 fmol/lane) comprising the promoter sequence. Lanes 1–4 contain no Irr; lanes 3 and 4 contain 0.6 µg BSA; lanes 5 and 7 contain 0.1 µg Irr; lane 6 and 11–13 contain 0.6 µg Irr; lane 8 contains 0.2 µg Irr; lanes 9 and 14–16 contain 0.3 µg Irr; lane 10 contains 0.4 µg. Reactions contain 1 mM MnCl₂ as indicated. Lanes 14–16 contain non-labeled DNA fragment <i>mbfA</i> in excess amount as cold competitor. Lanes 12 and 13 contain radioactively labeled <i>sitA</i> DNA fragment (180 bp) as unspecific DNA. (B) Binding of Irr to the promoter region of <i>ccpA</i> (168 bp). All reactions contain the same amount of ³²P end-labeled DNA fragment (3.68 fmol/lane) comprising the promoter sequence. Lanes 1–3 contain no Irr; lane 3 contains 0.6 µg BSA; lane 4 contains 0.1 µg Irr; lane 5 contains 0.2 µg Irr; lane 6 contains 0.4 µg Irr; lane 7 contains 0.6 µg Irr. Reactions contain 1 mM MnCl₂ as indicated. All reactions contain 1 µg of salmon sperm DNA as unspecific competitor. The asterisks and arrows show the location of free and Irr-bound ³²P end-labeled DNA fragments, respectively.