Fig. 1: Structures of DarR homologs.
a 1.6 Å resolution structure of the M. baixiangningiae DarR. One subunit is colored magenta and the other, green. Shown as sticks is the fortuitously bound ligand. Secondary structural elements are labeled for one subunit. b Top, superimposition of M. baixiangningiae DarR structure (green) onto the M. smegmatis structure (slate). Indicated below the structures is the distance between the recognition helices of each dimer (50 Å for the M. baixiangningiae DarR dimer and 41 Å for the M. smegmatis DarR dimer). Bottom, superimposition of the two M. smegmatis DarR dimers (one in slate and one in orange) that are present in the ASU showing they are essentially identical aside from loop regions. c Close-up of the fortuitously bound borate complex in the M. baixiangningiae DarR structure with Sigma-A weighted omit electron density (mFo-DFc) included (blue mesh) and contoured at 3.3 σ. The omit electron density was generated in Phenix by first removing the ligand and then subjecting the coordinates to 30 cycles of refinement to remove bias. The ligand and residues that bind the ligand are shown as sticks. d 2-D chemical structure of the Tris-borate-glycerol complex.
