Fig 8.

Effect of various amino acids on ald expression and binding of AldR to the ald control region. (A) M. smegmatis wild-type strain containing the ald::lacZ transcriptional fusion plasmid pALDLACZ was grown aerobically in 7H9 glucose medium to an OD₆₀₀ of 0.5 to 0.6. Following the addition of 25 mM l-amino acids, the strain was further grown for an additional 1 h. The ald promoter activities were measured by determining the β-galactosidase activity. All values provided are the averages of results from two independent determinations. Error bars indicate the deviations from the means. (B) EMSA with the 243-bp DNA fragment (6.7 nM) encompassing O1, O2, and O3 and purified AldR in the presence of 20 mM l-alanine (Ala), l-serine (Ser), or l-cysteine (Cys). 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.