The optimal gene sequence for optimal protein expression in Escherichia coli: principle requirements (A review article) (Received: 14 .04 .2006; Accepted: 16 .05 .2006) EL-Rashdy M. Redwan Protein Research Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, New Borg EL Arab 21934, Alexandria, Egypt. e-mail:
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ABSTRACT As an essential element in the drug discovery, development process and post-genomic structural biology, there remains a need for expression of large numbers of recombinant protein agents and targets from diverse genomes. Escherichia coli remain the host of choice for many of these applications due to its speed, ease of genetic manipulation, and high level of recombinant synthesis. Expression can often be achieved at levels higher than 30% of total cellular protein and following induction greater than 65% of the protein synthetic machinery of the cell may be dedicated to synthesis of the target protein. However, there is the risk of translational errors related to the presence of high frequencies or clusters of rare codons in the foreign recombinant mRNA. In the case of therapeutic protein biopharmaceuticals, even at low levels these microheterogeneities have the potential to manifest themselves in adverse immunogenic responses. At higher levels, translational errors may impact overall tertiary structure and functional activity. During gene design for optimal expression, the codon usage into the codons bias of E. coli genes should be adapted. Further, regions of very high (>80%) or very low (
