Synthetic refactor of essential genes decodes functionally constrained sequences in yeast genome

The relationship between gene sequence and function matters for fundamental and practical reasons. Here, yeast essential genes were systematically refactored to identify invariable sequences in the coding and regulatory regions. The coding sequences were synonymously recoded with all optimal codons to explore the importance of codon choice. The promoters and terminators were swapped with well-characterized CYC1 promoter and terminator to examine whether a specialized expression is required for the function of a specific gene. Among the 10 essential genes from Chr.XIIL, this scheme successfully generated 7 refactored genes that can effectively support wild-type-like fitness under various conditions, thereby revealing amazing sequence plasticity of yeast genes. Moreover, different invariable elements were identified from the remaining 3 genes, exampling the logics for genetic information encoding and regulation. Further refactoring of all essential genes using this strategy will generate comprehensive understanding of gene sequence choice, thereby guiding its design in various applications.