Document Type

Article

Publication Date

2-2018

Department

Biological & Earth Sciences

Abstract

Genetic circuit-based biosensors are useful in detecting target metabolites or in vivo enzymes using transcription factors (Tx) as a molecular switch to express reporter signals, such as cellular fluorescence and antibiotic resistance. Herein, a phenol-detecting Tx (DmpR) was employed as a critical tool for enzyme engineering, specifically for the rapid analysis of numerous mutants with multiple mutations at the active site of tryptophan-indole lyase (TIL, EC 4.1.99.1). Cellular fluorescence was monitored cell-by-cell using flow cytometry to detect the creation of phenolic compounds by a new tyrosine-phenol-lyase (TPL, EC 4.1.99.2). In the TIL scaffold, target amino acids near the indole ring (Asp137, Phe304, Val394, Ile396 and His463) were mutated randomly to construct a large diversity of specificity variations. Collection of candidate positives by cell sorting using flow cytometry and subsequent shuffling of beneficial mutations identified a critical hit with four mutations (D137P, F304D, V394L, and I396R) in the TIL sequence. The variant displayed one-thirteenth the level of TPL activity, compared with native TPLs, and completely lost the original TIL activity. The findings demonstrate that hypersensitive, Tx-based biosensors could be useful critically to generate new activity from a related template, which would alleviate the current burden to high-throughput screening.

First Page

Article 2659

Publication Title

Scientific Reports

Comments

Original citation:

1.Kwon, K.K., Lee, D.H., Kim, S.J., Choi, S.L., Rha, E., Yeom, S.J., Subhadra, B., Lee, J., Jeong, K.J., Lee, S.G. Evolution of enzymes with new specificity by high-throughput screening using DmpR-based genetic circuits and multiple flow cytometry rounds. Sci Rep 2018; 8:2659.

This is an open-access article.

At the time of publication, Dr. Bindu Subhadra was affiliated with the Korea Research Institute of Bioscience and Biotechnology.

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