Fig. 4.

The MglB positively charged tract determines the polar localization of MglB. a MglB features a positively charged tract opposite to the MglA-binding site. The left panel shows electrostatic potential calculated with APBS⁵⁰. The tract is delineated by a white line. The right panel shows the residues in this tract mutated in MglA^3M. The two views are rotated by 90°. b MglB^3M-NG has a diffuse localization. Localizations of MglB-NG and MglB^3M-NG are shown. Scale bar = 2 µm. c MglA-YFP retains polar localization in MglB^3M-expressing cells. Localization of MglA-YFP in cells expressing MglB or MglB^3M is shown. Scale bar = 2 µm. d MglB^3M blocks the action of a GTP-locked MglA mutant. The motility of MglA^Q82L-expressing cells was measured in mglB deletion or in mglB^3M-expressing strains. For each cell, motility is measured as the distance traveled from the origin for a time period of 45 min. Note that MglB^3M-expressing cells are mostly nonmotile while MglB^WT-expressing cells show two distinct populations, one nonmotile and one motile with reduced traveled distance to origin due to previously described pendulum movements. e Expression of MglB^3M blocks motility. Motility is measured as the mean square displacement (MSD) of single cells on agar. The average MSD of n trajectories and associated standard error of the mean are shown for the wild-type strain (n = 2658) and the MglB^3M strain (n = 3616). MglB^WT: DZ2 ΔmglB pSWU19-mglB^WT, MglB^3M: DZ2 ΔmglB pSWU19-mglB^3M. Source data for panel (e) are provided as a Source Data File.