Synthetic Suicide Genetic Circuit for Metabolite Screening
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Solution Overview
Problem
Current methods for screening metabolite-overproducing mutant strains are inefficient, particularly for metabolites that do not exhibit visible phenotypes, requiring complex experimental procedures and are not applicable to various strains.
Innovation Solution
A synthetic suicide genetic circuit comprising a riboswitch and a suicide gene is introduced into mutant strains, allowing for the selection of metabolite-overproducing strains based on growth rate changes, with the riboswitch activating or inhibiting the suicide gene depending on metabolite concentration, thereby distinguishing overproducing from non-producing strains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional screening methods are used for metabolite-overproducing mutant strains, then screening can be performed, but the process requires complex experimental procedures and is inefficient, particularly for metabolites that do not exhibit visible phenotypes
Solution Approach 1:
A synthetic riboswitch acts as an intermediary between the metabolite and the suicide gene expression. The riboswitch binds to the target metabolite and translates this binding event into a structural change that regulates transcription, thereby mediating the detection of metabolite concentration and controlling cell survival without requiring complex external screening procedures
Solution Approach 2:
The screening system performs self-detection and self-selection. Mutant strains automatically express or suppress the suicide gene based on their metabolite production capability through the riboswitch mechanism, enabling them to self-identify as overproducers or non-producers without external intervention or complex experimental procedures
2Adaptability or versatility
If a synthetic riboswitch coupled with a fluorescence protein reporter is used, then metabolite production can be detected, but the method is limited to metabolites that can be detected by fluorescence and requires FACS which is not universally applicable
Solution Approach 1:
The riboswitch-based suicide gene circuit provides a universal screening mechanism that can be applied to detect various different metabolites by simply changing the riboswitch sequence specific to each metabolite, while maintaining the same suicide gene (cytosine deaminase) and substrate (fluorocytosine) system across all applications, thereby achieving multi-functionality without increasing overall system complexity
Solution Approach 2:
The system detects metabolite concentration by changing the transcriptional state parameter (on/off) rather than measuring fluorescence intensity. This parameter change from quantitative fluorescence measurement to qualitative survival/desath binary outcome simplifies the detection system while maintaining versatility across different metabolite types
3Difficulty of detecting and measuring
If screening is based on visible phenotypes such as color development or fluorescence, then visual observation is possible, but this is limited to only several kinds of metabolites that show natural color development or fluorescence
Solution Approach 1:
The system replaces optical detection methods (color development, fluorescence) with a biochemical mechanism (riboswitch-metabolite binding followed by transcriptional regulation). This substitution eliminates the limitation of requiring metabolites to have optical properties, as the riboswitch can be designed to bind to any target metabolite through complementary base pairing or structural recognition, thereby expanding the range of detectable metabolites while maintaining ease of detection through simple growth observation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables efficient screening of metabolite-overproducing strains by visual observation of growth rates, allowing for the application to various strains and simplifying the screening process, as demonstrated by successful screening of GlcN6P and FMN overproducing strains.
Implementation Method 1
a first riboswitch that binds to the target metabolite
Implementation Method 2
the conversion of fluorocytosine to fluorouracil by cytosine deaminase induces cell death (apoptosis)
Implementation Method 3
an mRNA degradation mechanism in which a self-cleaving ribozyme is involved
Data Source
AI summary
The present invention relates to a method of screening a target metabolite-overproducing mutant strain using a synthetic suicide genetic circuit, and more particularly to a method of screening only a metabolite-overproducing mutant strain while killing a mutant strain that does not produce the metabolite, by introducing into mutant strains a synthetic suicide genetic circuit comprising a suicide gene coupled with a riboswitch. The method for screening a target metabolite-overproducing mutant strain according to the present invention has advantages in that a metabolite-overproducing mutant strain having a relatively fast or slow growth rate can be separated by visual observation, and in that the riboswitch that is used in the synthetic suicide genetic circuit can be replaced depending on the kind of target metabolite, and thus the synthetic suicide genetic circuit can be applied commonly to various strains.