High-yield Production of Granulocyte-macrophage Colony-stimulating Factor in BL21 (DE3) By an Auto-induction Strategy.

A novel strategy to increase protein expression yield is unintended induction of expression in complex media, called auto-induction. This method can be used to express proteins under control of the promoter without any need to monitor bacterial growth pattern, and addition of specific expression inducers such as Isopropyl β-D-1-thiogalactopyranoside (IPTG) at proper time. In the present study, a codon optimized gene encoding granulocyte-macrophage colony stimulating factor (GM-CSF) was cloned and over-expressed in BL21 (DE3) using both conventional inducer-based and auto-induction approaches in a shake flask scale and the yield of GM-CSF expression and biomass production was identified.

Improvement of soluble expression of GM-CSF in the cytoplasm of Escherichia coli using chemical and molecular chaperones.

The most common approaches to improve soluble expression of heterologous proteins are applications of molecular chaperones such as DnaK, DnaJ, GrpE, GroEL and GroES. The aim of present study was to enhance soluble expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) in Escherichia coli by different approaches including modification of cultivation and induction conditions, and thermally, genetically and chemically enhancement of expression of cellular chaperones. To genetically enhance amount of molecular chaperones, co-expression of pET28-GM-CSF and pKJE7 plasmids was performed.