Structures of the Inducer-Binding Domain of Pentachlorophenol-Degrading Gene Regulator PcpR from Sphingobium chlorophenolicum
AbstractPcpR is a LysR-type transcription factor from Sphingobium chlorophenolicum L-1 that is responsible for the activation of several genes involved in polychlorophenol degradation. PcpR responds to several polychlorophenols in vivo. Here, we report the crystal structures of the inducer-binding domain of PcpR in the apo-form and binary complexes with pentachlorophenol (PCP) and 2,4,6-trichlorophenol (2,4,6-TCP). Both X-ray crystal structures and isothermal titration calorimetry data indicated the association of two PCP molecules per PcpR, but only one 2,4,6-TCP molecule. The hydrophobic nature and hydrogen bonds of one binding cavity allowed the tight association of both PCP (Kd = 110 nM) and 2,4,6-TCP (Kd = 22.8 nM). However, the other cavity was unique to PCP with much weaker affinity (Kd = 70 μM) and thus its significance was not clear. Neither phenol nor benzoic acid displayed any significant affinity to PcpR, indicating a role of chlorine substitution in ligand specificity. When PcpR is compared with TcpR, a LysR-type regulator controlling the expression of 2,4,6-trichlorophenol degradation in Cupriavidus necator JMP134, most of the residues constituting the two inducer-binding cavities of PcpR are different, except for their general hydrophobic nature. The finding concurs that PcpR uses various polychlorophenols as long as it includes 2,4,6-trichlorophenol, as inducers; whereas TcpR is only responsive to 2,4,6-trichlorophenol. View Full-Text
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Hayes, R.P.; Moural, T.W.; Lewis, K.M.; Onofrei, D.; Xun, L.; Kang, C. Structures of the Inducer-Binding Domain of Pentachlorophenol-Degrading Gene Regulator PcpR from Sphingobium chlorophenolicum. Int. J. Mol. Sci. 2014, 15, 20736-20752.
Hayes RP, Moural TW, Lewis KM, Onofrei D, Xun L, Kang C. Structures of the Inducer-Binding Domain of Pentachlorophenol-Degrading Gene Regulator PcpR from Sphingobium chlorophenolicum. International Journal of Molecular Sciences. 2014; 15(11):20736-20752.Chicago/Turabian Style
Hayes, Robert P.; Moural, Timothy W.; Lewis, Kevin M.; Onofrei, David; Xun, Luying; Kang, ChulHee. 2014. "Structures of the Inducer-Binding Domain of Pentachlorophenol-Degrading Gene Regulator PcpR from Sphingobium chlorophenolicum." Int. J. Mol. Sci. 15, no. 11: 20736-20752.