Fig. 5: Binding and bundling of F-actin by XopR.

a Schematic domain illustration of four XopR truncation variants, EHWH2, HH, WH2, and WH2α. b MST binding curves of LatB-G-actin titrated with different XopR peptides with three biological replicates each. n = 3; Error bar, SD. c High-speed F-actin cosedimentation assay using MBP-EHWH2-msfGFP, MBP-HH-msfGFP, MBP-WH2-msfGFP, and MBP-WH2α-msfGFP. The data were fit using a Hill equation. d Negative stain electron microscopy (EM) of F-actin bundles formed by mixing 1 μM XopR with 0.2 μM F-actin in 150 mM NaCl. Scale bar from left to right: 400, 50, and 50 nm. e Micrographs of 0.2 μM F-actin in the presence of 10 μM XopR and XopRΔHH in the indicated NaCl buffer. F-actin was labeled with Acti-stain™ phalloidin. Scale bar = 5 μm. f Low-speed F-actin cosedimentation assay with XopR and XopRΔHH in the buffer with both 150 and 200 mM NaCl. g Low-speed cosedimentation assay of XopR full-length, XopR-IDR and XopR-Cter in 150 mM NaCl solution (n = 3 biological replicates). Data were presented as mean values ± SD. The data were fit using a Hill equation. h Representative time-lapse images of TIRF-actin polymerization over 480 s with 0.5 μM G-actin (10% Oregon-actin), 100 nM AtFH1-FH1C, and 400 nM XopR under 50 mM NaCl conditions. Scale bar = 2 μm for f.