Fig. 4
From: Heme and hemoglobin utilization by Mycobacterium tuberculosis
Heme binding by M. tuberculosis DppA and its atomic structure. a Purification of DppA from E. coli. Lanes: (1) E. coli lysate containing mbp6his-dppA expression vector, combined fractions after Ni(II)-affinity (2) and amylose affinity (3), (4) TEV cleavage of fusion protein and (5) purified DppA post TEV cleavage after Ni(II) recapture of MBP6His. b Heme binding of wild-type DppAMtb (black) and mutant DppAR179A (cyan) at varying heme concentrations determined by surface plasmon resonance (SPR) spectroscopy. Buffer controls do not show any signal for both proteins and are not visible because they overlap with the x-axis. The same heme concentrations were used for both proteins. Source data are provided in the Source Data file. c Ribbon diagram of Mtb DppA with N- and C-terminal halves of the protein color-coded in dark and light green, respectively. The ribbon diagram is overlaid to a semi-transparent solvent surface. d Magnified view of DppA α-helical hinge (residues 250–266) colored in red, which bears a striking resemblance to a clothespin spring. e Magnified view of DppAwt final 2Fo−Fc electron density map calculated at 1.27 Å resolution and overlaid to the refined model of DppA tetrapeptide (shown as sticks). The electron density is colored in blue and contoured at 1.7σ above background
