Rex directly binds to the promoters of a selection of upregulated genes.

A. EMSAs with purified Rex protein and promoter DNA fragments from the adhE, rex, ldh, gbs0609, purC, cdnP, menA and gbs0644 (cyl) genes. DNA fragments (30 nM) were incubated with the indicated concentrations (in nM) of Rex protein for 20 min at 30°C. Then, the protein-DNA complexes were resolved by electrophoresis on TBE polyacrylamide gels. As a negative control, an internal fragment of 170 bp from the gbs0455 gene, lacking rex binding site, was used as a DNA competitor (indicated by an asterisk). B. EMSAs were performed with the adhE promoter fragments (30 nM), Rex protein (600 nM), and the indicated concentrations of NADH. No Rex protein was added to the first lane. C. EMSAs were performed with the adhE promoter, as in A, but with different concentrations of NAD+. D. EMSAs were performed with the adhE promoter, as in B, but with different NADH and NAD+ concentrations.