Engineering Saccharomyces cerevisiae‐based biosensors for copper detection

Abstract

Heavy metals, that is Cu(II), are harmful to the environment. There is an increasing demand to develop inexpensive detection methods for heavy metals. Here, we developed a yeast biosensor with reduced‐noise and improved signal output for potential on‐site copper ion detection. The copper‐sensing circuit was achieved by employing a secondary genetic layer to control the galactose‐inducible (GAL) system in Saccharomyces cerevisiae. The reciprocal control of the Gal4 activator and Gal80 repressor under copper‐responsive promoters resulted in a low‐noise and sensitive yeast biosensor for copper ion detection. Furthermore, we developed a betaxanthin‐based colorimetric assay, as well as 2‐phenylethanol and styrene‐based olfactory outputs for the copper ion detection. Notably, our engineered yeast sensor confers a narrow range switch‐like behaviour, which can give a ‘yes/no’ response when coupled with a betaxanthin‐based visual phenotype. Taken together, we envision that the design principle established here might be applicable to develop other sensing systems for various chemical detections.

Multi-level engineering of Saccharomyces cerevisiae for the synthesis and accumulation of retinal

“…S2 †). The β-carotene producing yeast was based on the engineered strain with copper-regulated control of gene expressions via a secondary genetic layer as previously reported, 22 which enables β-carotene production using low concentrations of the copper ion as an inducer. As shown in Fig.…”

A Layered Genetic Design Enables the Yeast Galactose Regulon to Respond to Cyanamide

“…In this study, we also implemented a similar design to construct a strain JY-Cu with GAL4 under a copper-inducible promoter. 17 However, the high background level of P CUP1 promoter together with GAL4 signal amplifier resulted in a constitutive expression of EGFP even without copper inducer (Figure S1). To further confirm the homogeneity of EGFP expression across the cell population, we integrated the EGFP cassette into the yeast chromosome to avoid the plasmid variation, and the resulting strain JY-Cyan-EGFPint gave a uniform EGFP output based on the fluorescence microscopy analysis (Figure 2E).…”

“…The copper-inducible GAL systems that consist of the copper-induced expression of Gal4 and the copper-inhibited Gal80 repressor have been developed. 16,17 The layered genetic design enables the GAL system to respond to copper ion with a wide dynamic range, which can be used as an ultrasensitive biosensor for copper detection and for controlling host metabolism to produce chemicals. 16,17 Recently, a fast-acting and nearly gratuitous induction system based on the chimeric transcriptional activator Gal4DBD.ER.VP16 (GEV) was reported.…”

“…16,17 The layered genetic design enables the GAL system to respond to copper ion with a wide dynamic range, which can be used as an ultrasensitive biosensor for copper detection and for controlling host metabolism to produce chemicals. 16,17 Recently, a fast-acting and nearly gratuitous induction system based on the chimeric transcriptional activator Gal4DBD.ER.VP16 (GEV) was reported. 18 Upon addition of the hormone β-estradiol, cytoplasmic GEV localizes to the nucleus and binds to the GAL promoters to activate transcription.…”

“…To improve the transcriptional activity of Gal4, Zhou et al obtained a variant of Gal4 T406A/V413A with higher transcriptional activity compared to the wild-type Gal4 by means of combinatorial targeted mutagenesis, which enhanced the expression of the P GAL -driven genes and increased the yield of target metabolites. The copper-inducible GAL systems that consist of the copper-induced expression of Gal4 and the copper-inhibited Gal80 repressor have been developed. , The layered genetic design enables the GAL system to respond to copper ion with a wide dynamic range, which can be used as an ultrasensitive biosensor for copper detection and for controlling host metabolism to produce chemicals. , …”