Fig. 1.

Overproduced Y. enterocolitica and E. coli PspC proteins are stabilized in an E. coli ΔftsH mutant. E. coli strain AR3289 (ftsH⁺) and its isogenic ΔftsH derivative AR3291 (ΔftsH) contained empty lacZp expression plasmid pWSK29 (−) or derivatives encoding Y. enterocolitica PspC (↑ PspC-Ye) or E. coli PspC (↑ PspC-Ec). Cells were grown at 37°C for 3 h (Before Cm). Chloramphenicol was then added to block translation, followed by incubation for a further 2 h at 37°C (After Cm). Cell lysates were separated by SDS-PAGE and analyzed by anti-FtsH and anti-PspC immunoblotting. An unidentified E. coli protein that cross-reacted with the anti-FtsH serum served as a convenient loading control (LC).