Figure 2. Electron micrographs showing IssA assemblies in vitro.

(a) IssA is purified as nanoparticles of 20–300 nm as shown by negative stain TEM (scale bar is 50 nm). (b) Magnified region of a to match scale of c. (c) Treatment of IssA with guanidinium, EDTA and DTT yields a more uniform size distribution of 16–22 nm (scale bar is 50 nm). (d) Individual particles from c at higher magnification (scale bar is 25 nm).