REVIEW ARTICLE published: 01 April 2014 doi: 10.3389/fchem.2014.00015 Unnatural amino acid incorporation in E. coli: current and future applications in the design of therapeutic proteins Kim Wals and Huib Ovaa* Division of Cell Biology, Chemical Biology and Drug Innovation, The Netherlands Cancer Institute, Amsterdam, Netherlands Edited by: Unnatural amino acid (UAA) incorporation by amber codon suppression offers scientists Youla S. Tsantrizos, McGill a powerful tool to modify the properties of proteins at will. UAA incorporation has University, Canada been used for a plethora of fundamental research applications and, more recently, Reviewed by: also for the selective modification of therapeutic proteins. In this review most recent Minkui Luo, Fudan University, China John F.Honek, University of developments in Escherichia coli codon expansion and, unnatural amino acid incorporation Waterloo, Canada are discussed together with some remarkable recent developments in improved efficient Martin Schmeing, McGill University, UAA incorporation. We focus on the generation of proteins that hold promise for future Canada therapeutic applications that would be impossible to obtain without unnatural amino *Correspondence: acid incorporation, including the generation of bi-specific antibodies and antibody drug Huib Ovaa, Division of Cell Biology, The Netherlands Cancer Institute, conjugates. Plesmanlaan 121, 1066CX, Keywords: unnatural amino acid incorporation, Escherichia coli, amber codon suppression, release factor 1, Amsterdam, Netherlands therapeutic proteins, antibody conjugates, chemical protein modifications e-mail:
[email protected] INTRODUCING MODIFICATIONS IN Escherichia. coli protein modifications. If, for example, glycosylation of a recom- PRODUCED PROTEINS binant protein is required, specialized E. coli strains can be used E. coli is the protein production workhorse of many scientists as E.