Figure 5 : Effect of domain exchange between the MotAB and MotPS stators on motor performance of the Bacillus motor.

From: Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor

Figure 5

(a) MotA and MotP have four transmembrane (TM) helices and a large cytoplasmic loop between TM2 and TM3. The PS-L motor was constructed by exchanging the cytoplasmic loop of MotP with that of MotA. Conserved residues and critical charged residues are shown by black boxes and asterisks, respectively45. MotB and MotS have a single TM helix and a C-terminal large periplasmic domain containing a PG binding motif (OmpA-like domain), which is critical for stator assembly around the rotor46. The PS-p1, PS-p2 and PS-p3 motors were constructed by the exchange of the indicated region of MotS with the corresponding region of MotB. The AB-p3 motor was constructed by exchanging the OmpA-like domain of MotB with that of MotS. (b) Torque-speed relationship of the PS-L (square), PS-p2 (triangle) and PS-p3 (circle) motors in the presence of 200 mM NaCl. Rotation measurements were done by tracking the position of 1.5-μm, 1.0-μm, 0.8-μm, 0.6-μm and 0.5-μm beads. The torque-speed curve of the MotAB motor is shown by magenta line. (c) Torque-speed relationship of the AB-p3 motor in the presence of 200 mM NaCl (square) or KCl (circle) condition. Rotation measurements were carried out by tracking the position of 2.0-μm, 1.5-μm, 1.0-μm, 0.8-μm, 0.6-μm and 0.5-μm beads. The torque-speed curve of the MotPS motor is shown by blue line.