Context effects of genetic code expansion by stop codon suppression

• Published in: Current opinion in chemical biology 2018-10, Vol.46, p.146-155
• Main Authors: Chemla, Yonatan, Ozer, Eden, Algov, Itay, Alfonta, Lital
• Format: Article
• Language: English
• ISSN: 1367-5931; 1879-0402
• DOI: 10.1016/j.cbpa.2018.07.012

[Display omitted] •Genetic code expansion by stop codon suppression is significantly influenced by context effects.•The context effects are divided into three sub-groups: mRNA, operon and cellular context.•mRNA context effects should be separated to stop codon suppression and release factor effects.•Absence of off target stop codon suppression reveals that native terminal stop-codons have high termination efficiency.•Practical considerations for genetic code expansion by stop codon suppression are presented. Genetic code expansion enables the incorporation of unnatural amino acids into proteins thereby augmenting their physical and chemical properties. This is achieved by the reassignment of codons from their original sense to incorporate unnatural amino acids. The most commonly used methodology is stop codon suppression, which has resulted in numerous successful studies and applications in recent years. In these studies, many observations have been accumulated indicating that stop codon suppression efficiency depends on various cellular, operon and mRNA context effects. Predominant among these are mRNA context effects: the location of the stop codon along the mRNA governs, to a large extent, the efficiency and ability to successfully incorporate unnatural amino acids. Albeit their prevalence and importance, the mechanisms that govern context effects remain largely unknown. Herein, we will review what is known and yet to be understood with the intent to advance the propagation of genetic code expansion technology and to stimulate systematic research and debate of this open question.