High-resolution deep-etch EM micrographs of curliated E. coli and purification of curli fibers. (A and B) Representative freeze-fractured micrographs that have been rotary shadowed with platinum. The inset in (A) shows curli fibers. (C) MC4110 was absorbed onto glass and deep-etched without being fractured before rotary shadowing with platinum. (D) Coomassie stain SDS-PAGE of curli samples isolated from E. coli strain MC4100. Lanes 1 and 2 contain 40 mg of S6 wild-type curli without and with FA treatment, respectively. Lane 3 contains 20 mg of FA-treated GP curli. Molecular size markers (inkilodaltons) are indicated on the left. (E) Negative-stain EM micrographs of MC4100 grown on YESCA plates at 26°C for 48 hours. (F) Negative-stain EM micrograph of purified wild-type S6 curli. Bars: (A), 400 nm; (B) and (C), 60 nm; (E) and (F), 200 nm.