Improving production of N-glycosylated recombinant proteins by leaky Escherichia coli

Escherichia coli has been considered as a promising host for the production of N-glycosylated therapeutic proteins and glycoconjugate vaccines. In this study, we developed a simple and efficient strategy for improving the production of N-glycosylated recombinant proteins by combining auto-induction with the use of a leaky E. coli strain. A leaky E. coli strain, designated as CLM37-Δlpp, was engineered by deleting the Braun's lipoprotein (lpp) gene of E. coli strain CLM37. Three distinct acceptor model N-glycosylated proteins, glyco-tagged human tenth fibronectin type III domain (FN3-Gly), enhanced green fluorescent protein (eGFP-Gly), and scFv of vascular endothelial growth factor receptor 3 (scFv-_VEGFR3-Gly) were then expressed in CLM37-Δlpp, which carried an N-glycosylation machinery from Campylobacter jejuni for the investigation of glycoprotein production. As much as 75%, 65%, and 60% of the glycosylated FN3-Gly, eGFP-Gly, and scFv-_VEGFR3-Gly, respectively, were found in the culture medium. The yields of glycosylated FN3-Gly, eGFP-Gly, and scFv-_VEGFR3-Gly were 106 ± 7.4 mg/L, 65 ± 2.5 mg/L, and 62 ± 4.3 mg/L, respectively, which were more than three folds the corresponding yields obtained when these proteins were expressed in CLM37, the unmodified strain. The results suggested that this simplified approach could improve the production of N-glycosylated proteins with E. coli to facilitate large-scale production.