Fig. 13

Effects of Spr accumulation on bacterial motility, FliC expression and the activation of the extracytoplasmic signaling systems. (a) The levels of Spr and FliC in the RS218 strains with or without prc. To detect Spr, these strains were modified to express C-terminally 3xFlag-tagged Spr. Western blot analyses with an anti-Flag antibody and a rabbit anti-FliC antiserum were performed to detect the protein levels. The OmpA levels served as loading controls, which were probed with a mouse anti-OmpA antiserum. Spr-3xFlag-RS218, the RS218 strain with the native chromosomal spr fused with a sequence encoding a 3xFLAG tag at the 3′ end; Spr-3xFlag-Δprc-RS218, the Δprc-RS218 strain with the chromosomal spr fused with a sequence encoding a 3xFLAG tag at the 3′ end. (b) The FliC and Spr levels in the RS218 strains with or without the overexpression of the recombinant Spr, which was C-terminally fused with a Flag tag. The Spr protein was detected with an anti-Flag antibody. Arabinose (0.2%) was used to trigger the expression of the recombinant Spr that was encoded in pBAD and driven by the arabinose-inducible promoter in the plasmid. pSpr, pBAD harboring spr fused with a sequence encoding a Flag tag at the 3′ end. (c) Motility diameters of the strains overexpressing Spr. (d) The relative mRNA levels of yiiS and yjbE compared to those in WT-RS218/pBAD. (e) The relative yibE levels compared to those in WT-RS218. (f) The FliC level in WT-RS218, Δprc-RS218, and ΔsprΔprc-RS218. (g) Motility diameters of WT-RS218, Δprc-RS218, and ΔsprΔprc-RS218