Figure 2 : X. fastidiosa outer membrane vesicle (OMV) visualization and protein cargo analysis.

From: The Type II Secreted Lipase/Esterase LesA is a Key Virulence Factor Required for Xylella fastidiosa Pathogenesis in Grapevines

Figure 2

(A) Electron micrograph of negatively stained outer membrane vesicles extracted from the Xff Temecula1 cell free supernatant. Both small (left; <200 nm diameter) and large (right; up to 400 nm diameter) OMVs were identified. The black arrow indicates the outer membrane, which was released from the bacterial cell, presumably enclosing periplasmic content to produce the OMV. Large OMVs contained an electrodense material of unknown composition that was not seen in small OMVs. (B) Silver-stained SDS-PAGE 12% separation of OMV cargo showing a band at apparent molecular weight 42 KDa, presumed to be composed of proteins LesA, PD1702, and MopB, all found in the OMV proteomic analysis (Table S1). (C–E) Immunoblot detection of LesA, MopB, and EF-Tu in Xff total proteins (TP), outer membrane proteins (OMP), soluble supernatant proteins (SSP), and outer membrane vesicle proteins (OMV). For TP, OMP and SSP (defined in Fig. 1A), 10 μg protein was loaded in the gel; however, only 2 μg protein was loaded in OMV due to the high non-protein content of this sample. This may explain the weak detection of LesA in C.