Production of Recombinant Proteins in an Insertion Sequence-free Escherichia coli MS56

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Myung Keun Park

Korea Advanced Institute of Science and Technology, South Korea

The genomic stability and integrity of host strains are critical for the production of recombinant proteins in biotechnology because genomes of such microorganisms contain numerous insertion sequences (ISs) that cause a variety of genetic rearrangements, resulting in adverse effects such as instability of genomes and recombinant clones. To minimize the harmful effects of ISs on the expression of recombinant proteins in Escherichia coli, we recently developed an IS-free minimized E. coli strain (MS56) in which all ISs and many unnecessary genes were removed from the E. coli MG1655 genome. Here, we compared the expression profiles of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and bone morphogenetic protein-2 (BMP2) in MG1655 and MS56. The hopping of ISs (IS1, IS3 or IS5) into the genes encoding TRAIL and BMP2 occurred at the rate of ~10-8/gene/h in MG1655 whereas no IS hopping was observed in MS56. Even though IS hopping occurred very rarely (-10-8/gene/h), the IS-inserted TRAIL and BMP2clones became dominant in 28 h, significantly reducing recombinant protein production in batch fermentation. Cells harboring IS-inserted clones grew much faster than the IS-free clones. Our findings clearly indicate that IS hopping is detrimental to the industrial production of recombinant proteins and that the development of IS-free host strain (MS56) is highly desirable for the production of recombinant proteins.