Activities of 20 aminoacyl-tRNA synthetases expressed in a reconstituted translation system in Escherichia coli

• We expressed 20 aminoacyl-tRNA synthetases in a reconstituted translation system.
• All aminoacyl-tRNA synthetases (aaRSs) are expressed as soluble proteins.
• All aaRSs with the exception of phenylalanyl-tRNA synthetase are active.
• Their activities are comparable to those expressed in E. coli.

A significant challenge in the field of in vitro synthetic biology is the construction of a self-reproducing cell-free translation system, which reproduces its components, such as translation proteins, through translation and transcription by itself. As a first step for such construction, in this study we expressed and evaluated the activity of 20 aminoacyl-tRNA synthetases (aaRSs), a major component of a translation system, in a reconstituted translation system (PURE system). We found that 19 aaRS with the exception of phenylalanyl-tRNA synthetase (PheRS) are expressed as soluble proteins and their activities are comparable to those expressed in Escherichia coli . This study provides basic information on the properties of aaRSs expressed in the PURE system, which will be helpful for the future reconstitution of a self-reproducing translation system.