Fig 7.

Binding of purified AldR to the ald control region. (A) The 243-bp DNA fragment (10 ng, corresponding to 6.7 nM) encompassing the O1, O2, and O3 sequences was incubated with various concentrations of purified AldR in the presence (+Ala) or absence (−Ala) of 20 mM l-alanine. The concentrations of AldR used are given above the lanes. Native PAGE was run in the presence of 83 mM Tris-borate buffer (pH 8.3) containing 1 mM EDTA, and the gels were stained with SYBR green EMSA gel staining solution. The arrows indicate bands of free DNA and retarded AldR-DNA complexes. (B) Ten ng of each of the DNA fragments (10 ng corresponds to 6.7 nM for control, 7.5 nM for ΔO1, and 6.9 nM for ΔO1O2), which contain O1, O2, and O3 (control), both O2 and O3 (ΔO1), and only O3 (ΔO1O2), were incubated with various concentrations of purified AldR in the presence of 20 mM l-alanine and subjected to native PAGE.