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. 2015 May 21;6:7125. doi: 10.1038/ncomms8125

Figure 2. Intermolecular SPOA1–SPOA2 interactions are not necessary for T3SS function.

Figure 2

(a) Schematic models for putative intra- and intermolecular SPOA1–SPOA2 interactions and their implications for the SpaO oligomerization state. The numbers 1 and 2 indicate the SpaO SPOA1 and SPOA2, respectively, and N indicates the SpaO amino-terminal domain(s). (b) Coomassie-stained polyacrylamide gel electrophoresis (PAGE) of S. typhimurium culture supernatants grown under T3SS-stimulating conditions (0.3 M NaCl, strain SB1741). Bands previously identified by Mizusaki et al.13 are noted and colour coded by the T3SS subtype—injectisome in red and flagellar in blue. (c) Coomassie-stained PAGE of S. typhimurium culture supernatants grown under T3SS-stimulating conditions. Red asterisks indicate injectisome-specific secretion substrates. WT, wild type; ΔO, deletion of spaO; Δ1–203, deletion of spaO codons 1–203; 1–219, complementation with SpaO(1–219); 1–219stop, insertion of two stop codons following spaO codon 219. SpaO was 3 × FLAG tagged at its amino terminus in each S. typhimurium strain (except ΔO) and complementation construct. Data shown are representative of three experiments.