Modular, synthetic chromosomes as new tools for large scale engineering of metabolism

The construction of powerful cell factories requires intensive genetic engineering for the addition of new functionalities and the remodeling of native pathways and processes. The present study, using Saccharomyces cerevisiae, explores the potential of modular, specialized de novo-assembled neochromosomes (named NeoChrs) to facilitate extensive genome reprogramming. Linear and circular NeoChrs carrying 20 native and 21 heterologous genes were designed and constructed by in vivo assembly in yeast in two transformation steps, leading to the production of anthocyanins, native to plants. Turned into exclusive expression platforms for heterologous and essential metabolic routes, the NeoChrs behaved like native chromosomes regarding mitotic and genetic stability, copy number, harmlessness for the host and editability by CRISPR-Cas. This study paves the way for future microbial cell factories with modular genomes in which core metabolic networks, localized on satellite, specialized NeoChrs can be swapped for alternative configurations and serve as landing pads for addition of functionalities.