A Toolkit for Rapid Modular Construction of Biological Circuits in Mammalian Cells

João Pedro Fonseca; Alain R. Bonny; G. Renuka Kumar; Andrew H. Ng; Jason Town; Qiu Chang Wu; Elham Aslankoohi; Susan Y. Chen; Patrick Harrigan; Lindsey C. Osimiri; Amy L. Kistler; Hana El-Samad

Additionally, the MTK allows for further fine-tuning of a TU in a given range using a collection of five different 3' UTR sequences. Similar to the promoter comparison, we generated a circuit with the same constitutive promoter (EF1a) and varied the 3' UTR sequence to compare normalized mAzamiGreen expression (Fig. 2b) . We observed a range of 4-fold change in expression of mAzamiGreen among the three conventional 3' UTR sequences. While the Bgh pA and Rgl pA signals are redundant, the simian virus 40 (SV40) pA signal has a nearly 1.5-fold greater effect on expression than the other pA sequences (Fig. 2c) . This supports the notion that by rationally varying promoter-pA combinations, one can fine-tune incremental changes in expression to complement the log-scale changes accompanied by solely changing promoters.