Enhanced production of full-length immunoglobulin G via the signal recognition particle (SRP)-dependent pathway in Escherichia coli

• Full-length IgG were produced in E. coli host.
• By combining SRP/Sec pathways, heavy and light chains could be produced much more efficiently.
• By co-expression of DsbC and Ffh, production yield of IgG could be significantly improved.
• By fed-batch cultivations, E. coli cells produce 62 mg/L of full-length IgG.

Because of the lack of post-translational glycosylation, Escherichia coli is not a preferable host for immunoglobulin G (IgG) production. However, recent successes in the developments of aglycosylated IgG variants that do not require glycosylation for effector functions have increased the likelihood of using E. coli for IgG production. Here, we have developed a new E. coli host–vector system for enhanced production of recombinant IgG using: (i) a combination of SRP/Sec-dependent pathways for the efficient secretion of heavy and light chains in the periplasm; (ii) co-expression of periplasmic foldase (DsbC) for efficient assembly of IgG in the periplasm; and (iii) co-expression of Ffh for enhancing the SRP machinery. Finally, with engineered host–vector system, fed-batch cultivations were conducted at four different conditions, and under an optimized condition, up to 62 mg/L of active full-length IgG was produced during a 28-h cultivation.