(A) Size distribution of WT Salmonella MVs; x-axis represents MV size ranges (100 represents 1-100nm2). Compared to WT MVs, size distribution of (B) ompF MVs and (C) ompA MVs is similar (p>0.05; also ompC, nmpC, and ompX MVs, data not shown), while (D) tolA MV size is significantly increased (p<0.001; also pal and tolB MVs, data not shown). (E) WT MVs are released at constricted division septa and (F) along the cell body. (G) MVs are released along the cell body in the absence of OmpA (shown) and LppAB (), and (H) MV release occurs at division septa in tolA (shown), pal (), and tolB (data not shown) mutant strains. (I) Major MV proteins classified by envelope interconnections: Integral OM proteins OmpC, OmpF, OmpX, and NmpC lack extensive connectivity to envelope components, Lpp and OmpA bind PG (OM-PG linked), and Pal, TolB, and TolA form membrane-spanning protein complexes (OM-PG-IM linked). Dark shading represents N-termini, straight lines represent non-covalent interactions, and zig-zag line denotes covalent interaction. Bars = 200nm (except F inset, bar = 100nm), n = number of individual vesicles examined.