The tRNA neochromosome contains all 275 nuclear tRNA genes of yeast. Its design is based on rational principles and it will be the sole source of tRNA expression in the final Sc2.0 strain. A neochromosome is defined as a synthetic chromosome that has no natural counterpart but has all the characteristics of a chromosome within a cell. It has a copy number of one and replicates in a cell cycle dependent manner.

Since the tRNA neochromosome has no natural counterpart, it was designed from scratch using rational synthetic and engineering biology principles. To reduce the risk of unwanted recombination with the yeast chromosomes, most of the DNA sequences are orthologous from other yeast species. Only the tRNA genes themselves are derived from S. cerevisiae. This tRNA neochromosome has now been constructed and characterized. It serves as a landmark example for the design of neochromosomes and will allow us to address questions in tRNA biology that were previously impossible.

tRNA neochromosome design

tRNA neochromosome synthesis and assembly plan