Library and Model Derived Synthetic Terminators for Yeast

Control of transcription and translation are critical parts of yeast synthetic biology and metabolic engineering.  While significant efforts have historically focused on the engineering of promoter elements, more recent attention has shifted toward terminator elements as a means to influence mRNA half-life and resulting protein expression.  Our group has recently demonstrated that short, synthetic terminator sequences (ranging from 35 to 70 bp in length) can result in superior synthetic parts for the yeast Saccharomyces cerevisiae.  We show that these more minimal elements (nearly an 80% reduction in sequence space) increase transcript levels nearly 4-fold over commonly used terminators such as CYC1.  We then show that these short, minimal terminators can function across different fungal host systems.  In an effort to move toward the model-based design of these elements, we have extracted a functional model effective at de novo design of these terminators.  We demonstrate the utility of this model by establishing a library of synthetic terminator elements with a range of activity.  In doing so, we create some of the first model-specified terminator elements for yeast.  This work both expands the set of synthetic parts available for fungal systems as well as provides insights into the sequence properties and underlying mechanisms of yeast transcriptional termination.