Pathway analysis of recombinant Escherichia coli during protein production process under simulated microgravity

Microgravity effects were reported to affect the physiological characteristics and perturbations at the molecular levels of the microorganisms. Our previous works reported that the recombinant β-glucuronidase (PGUS) expressing strain Escherichia coli BL21 (DE3)/pET28a-pgus grew faster and the efficiency of recombinant protein production was also enhanced under simulated microgravity (SMG) as compared with the normal gravity (NG). In this study, a quantitative proteomic analysis of triple stable isotope dimethyl labeling using mass spectrometry method to investigate the effects of SMG on the strain and the during recombinant protein production process was performed. A total of 124 differentially expressed proteins under SMG were identified as compared with NG. Among them, 92 proteins were significantly up-regulated and 6 proteins were drastically down-regulated under SMG. The majority of the up-regulated proteins were involved with the metabolism of cell stress response, amino acid metabolism, translation, transcription and carbohydrate metabolic process. The results indicated that the differentially expressed levels of these proteins under SMG were beneficial to the synthesis of the heterologous protein expression of the recombinant Escherichia coli.