FIG. 1.

CS phenotype and membrane topology of the YidC mutants. (A) CS phenotype of the yidC mutants. The JS7131 strain bearing the CS yidC(C423R), yidC(P431L), and wild-type yidC alleles on a low-copy-number pACYC184 plasmid was streaked on LB plates containing glucose (0.2%) or arabinose (0.2%) and incubated at 30°C for 2 days or at 37°C overnight. Each half of a plate contains three streaks from three individual colonies bearing the same construct. (B) The orientation of YidC in the plasma membrane of E. coli (16) and the locations of the CS mutations (amino acids 431 and 423) and suppressor mutation (residue 362) are indicated. (C) The amino acid sequences of YidC family members are indicated with the position of the CS mutation highlighted. In the family members, the CS mutations are predicted to be localized within the TM region, TM3 in E. coli and many gram-negative bacterial YidC proteins and TM2 in mitochondrial, chloroplasts, and most gram-positive bacterial YidC members. The top five sequences are YidC proteins from gram-negative bacteria; the next five sequences are from gram-positive bacteria; the YidC homologs in chloroplasts (Alb3) and mitochondria (Oxa1) are shown at the bottom. Cyt, cytoplasm; Peri, periplasm; IM, inner membrane.