Protein Purification and Antibody Production

The E. coli strains (Table S1), plasmids (Table S2), and PCR primers (Table S3) used in this study are listed. SecA^{40 (link)} and SecB^{41 (link)} were purified as described. Antibodies against MPIase^{7 (link)}, SecB^{42 (link)}, SecD^{27 (link)}, SecG^{43 (link)} and OmpA^{44 (link)} were raised in rabbits using the respective purified factors, while those against CdsA (Glu75~Ser92), M13 procoat (Ala24~Tyr44), LolC (Lys239~Glu255)^{28 (link)}, and YidC (Lys382~Gln402) were raised against synthetic peptides corresponding to the specified regions. All the antibodies were obtained through the commercially available custom services. [Glycerol-¹⁴C(U)]-L-α-dipalmitoyl-phosphatidic acid (3.7~7.4 GBq/mmol), [¹⁴C(U)] palmitic acid (>18.5 GBq/mmol), and [³⁵S] EXPRESS Protein Labeling Mix, a mixture containing both [³⁵S] Met and [³⁵S] Cys (~37 TBq/mmol), were obtained from Perkin Elmer, Inc. CDP-DAG, PA, PG and PE were from Avanti Polar Lipids, Inc. CL, GlcNAc-P, UDP-GlcNAc and L-arabinose were obtained from Sigma-Aldrich. CTP was from Roche Diagnostics. IPTG was from Wako Pure Chemical Industries, Ltd. CDP-GlcNAc (Supplementary Fig. 18) and the authentic reference of compound I (Supplementary Fig. 19) were chemically synthesized as described under Supplementary Methods. Protein A Sepharose was from GE Healthcare Life Sciences. TLC plates were from Merck.