It is a routine task in metabolic engineering to introduce multicomponent pathways into a heterologous host for production of metabolites.However, this process sometimes may take weeks to months.Here we present a method for the design and construction of biological parts based on the native genes and regulatory elements in Saccharomyces cerevisiae.We have developed highly efficient protocols (termed YeastFab Assembly) to synthesize these genetic elements as standardized biological parts, which can be used to assemble transcriptional units in a single-tube reaction.In addition, standardized characterization assays are developed using reporter constructs to calibrate the function of parts.Furthermore, the assembled transcription units can be either assayed individually or applied to construct multi-gene metabolic pathways,which targets a genomic locus or a receiving plasmid effectively, through a simple in vitro reaction.Finally, using β-carotene biosynthesis pathway as an example, we demonstrate that our method allows us not only to construct and test a metabolic pathway in as few as seven days, but also to optimize the production through combinatorial assembly of a pathway using hundreds of regulatory biological parts.