Rewriting the Genome of the Model Eukaryote Saccharomyces cerevisiae

An international consortium of scientists has embarked on the total design and synthesis of all the 16 yeast chromosomes of the laboratory organism, Saccharomyces cerevisiae. Once constructed, the 16 synthetic chromosomes will be consolidated into a single yeast strain along with a new 17th yeast chromosome called the “neochromosome” which contains all the tRNA genes, to generate a designer eukaryotic genome, Sc2.0. The key criterion for the stream-lined yeast (Sc2.0) is that it should retain the same cell fitness and phenotype of the wild-type (Sc1.0), but show increased genetic stability and flexibility to enable future studies. All the 16 synthetic yeast chromosomes have been designed using BioStudio, an open-source framework that was developed specifically to design and construct chromosome-size fragments in silico. The completely redesigned Sc2.0 genome is a highly modified version of the S. cerevisiae genome, with a reduction in the size of ∼1.1 million base pairs, which is about 8% of the native genome. In 2017, the Sc2.0 consortium reported the complete synthesis and assembly of 6.5 individual yeast chromosomes in discrete strains and showed consolidation of 2.5 synthetic chromosomes (synIII/synVI/synIXR) into a single yeast strain that bodes well for the successful completion of the Sc2.0 genome.