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Fine Regulation of Linker Sequences on the Yeast Synthetic Terminator Strength.

The design of improved synthetic parts is an important research field of synthetic biology. The terminator responsible for terminating gene transcription is a necessary part for yeast gene expression. The efficiency element, positioning element and poly(A) site are identified as the necessary elements for yeast terminator to perform function. However, the function on the linker 1 and the linker 2 in the terminator are still controversial. Here, we thus designed and synthesized a yeast synthetic terminator library with a random 10 bp linker 1. Through characterizing the strength of 266 synthetic terminators by the enhanced green fluorescent protein (eGFP), the actual FI value was determined ranging from 2.3648 to 3.5270, indicating that the strength of yeast terminator can be fine adjusted by changing the linker 1 sequence. The strength increased with the decrease of GC content in the linker 1, and the T-rich linker 1 helps to enhance terminator strength. Reducing the stem length can increase the gene expression for weak and medium terminator but will decrease the gene expression of strong terminator. The deletion of linker 2 seems to have a positive effect on weak and medium-strength terminators. Construction of lycopene biosynthesis pathway by synthetic terminators had effectively regulated lycopene synthesis, indicating that it is very feasible to use terminators to fine regulate gene and pathway expression.