Fig. 2.

XadA1 localizes to the cell envelope and to OMVs. (A) Anti-XadA1 antibody detects XadA1 in total cell lysates of WT X. fastidiosa (arrow) but not in lysates from a ΔxadA1 mutant. (B) XadA1 is present in both cells and cell-free supernatant of broth cultures (Top). XadA1 present in cell-free supernatant remains in suspension following low-speed (38,000 × g) centrifugation (Middle) but is removed as a pellet during high-speed (150,000 × g) centrifugation (Bottom). The dashed arrow indicates a cross-reacting polypeptide detected only in cells. (C) Deconvolution microscopy of WT cells (Left) and a ΔxadA1 mutant (Right) treated with both an anti-XadA1 antibody and DAPI, following a red-fluorogenic secondary antibody, revealing that XadA1 localizes to both the cell envelope and to the extracellular environment of cells, presumably in OMVs.