FIG. 2.

Degradation profiles of PhoA-TM8-C₃₀ (with a folded PhoA domain) and PhoA[SSSS]-TM8-C₃₀ (with an unfolded PhoA domain). Plasmid pCH309 (PhoA-TM8-C₃₀) was introduced into AR5087 (ftsH⁺; lanes 1 to 4 and 9 to 12) and AR5090 (ΔftsH; lanes 5 to 8 and 13 to 16), whereas plasmid pCH317 (PhoA[SSSS]-TM8-C₃₀; lanes 17 to 24) was introduced into AD1635 (ftsH⁺ ΔdegP; lanes 17 to 20) and AD1625 (ΔftsH ΔdegP; lanes 21 to 24). Cells were grown in M9 medium at 37°C and induced for lac transcription for 10 min. They were then pulse-labeled with [³⁵S]methionine for 1 min, which was followed by a chase with unlabeled methionine for 1 (lanes 1, 5, 9, 13, 17, and 21), 8 (lanes 2, 6, 10, 14, 18, and 22), 16 (lanes 3, 7, 11, 15, 19, and 23), and 32 (lanes 4, 8, 12, 16, 20, and 24) min. Labeled proteins were immunoprecipitated with anti-PhoA (lanes 1 to 8 and lanes 17 to 24) or anti-SecYC5 (lanes 9 to 16) antibodies, separated by SDS-PAGE, and visualized. PhoA∗ and PhoA∗∗ indicate degradation products produced from PhoA-TM8-C₃₀. PhoA-TM8-C₃₀ gave essentially the same degradation patterns as shown in lanes 1 to 4, when it was expressed in AD1635 lacking DegP.