BIOT 79 |
| The advent of recombinant DNA technology has revolutionized the strategies for protein production. Escherichia coli is still the most common workhorse for recombinant protein production. Recently, targeting recombinant proteins in the extracytoplasmic compartment has gained much attention. Periplasm has a special environment suitable for the formation of eukaryotic proteins and an isolated compartment significantly facilitating downstream protein purification. On the other hand, displaying polypeptides on E. coli cell surface has been extensively studied due to its potential for various novel biotechnological and industrial applications. Nevertheless, targeting polypeptides in the extracytoplasmic compartment often induces local stresses, resulting in physiological deterioration and poor expression performance, and developing the strategies to overcome this technical hurdle warrants more systematic exploration. A prerequisite to physiological improvement is that cell physiology needs to be properly monitored. In the research area of recombinant protein production, cell physiology is recognized as a vague term generally in correlation with cell's health, viability, metabolic activity, and protein-producing ability. The presence of an excess amount of the foreign gene products and the environmental impact can impose physiological challenges on the protein-overproducing cells. The response to the extracytoplasmic stress is driven by the synthesis of a variety of stress-responsive proteins expressing protease and/or chaperone activities. As a practical application, these proteins can be used not only as ‘sensors' for monitoring cell physiology but also as suppressors for alleviating physiological stress. In this presentation, alleviation of the extracytoplasmic stress to improve both cell physiology and recombinant protein production will be demonstrated as an exploration of the natural defense system for industrial applications. Monitoring the extracytoplasmic stress using the fusions of a selection of stress-responsive promoters with a reporter gene will be described in two cases of recombinant protein targeting in the periplasm and on the outer membrane. |
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Upstream Processing: Advances in Microbial Fermentation Process Development
8:00 AM-10:15 AM, Monday, August 20, 2007 BCEC -- 106, Oral
Division of Biochemical Technology |