Figure 9.

DNA looping by GalR and LacI. (A) Repressome formation by GalR-O_E and GalR-O_I interactions with HU (blue) and supercoiled DNA. DNA looping repressed both P1 and P2; (B) DNA looping by LacI binding to lac operators; (C) The in vivo level of galactokinase, a product of the gal operon is reported as repressed or constitutive in the presence of GalR and LacI on ${{\displaystyle O}}_E^G-{{\displaystyle O}}_I^G$, ${{\displaystyle O}}_E^G-{{\displaystyle O}}_I^L$, ${{\displaystyle O}}_E^L-{{\displaystyle O}}_I^G$ and ${{\displaystyle O}}_E^L-{{\displaystyle O}}_I^L$ templates. GalR is in light green and LacI is in dark green. The gal operators are in grey rectangular boxes, while the lac operators are in black rectangular boxes (adapted from [66]).