Yeast Protein Depletion via N-degron and Hormone-Inducible Protease
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Solution Overview
Problem
Current methods for controlling protein abundance in eukaryotes, such as traditional perturbation techniques, often result in side effects and are not capable of specifically turning on or off a single transcription factor, leading to deleterious effects on gene expression and physiology.
Innovation Solution
A novel method involving genetically modified yeast cells with a DNA construct that introduces a degradation signal (N-degron) at the amino-terminus of target proteins, using a hormone-responsive transcription factor and protease-encoding gene to induce specific protein degradation upon hormone exposure, allowing for rapid and targeted protein depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional perturbation methods (heat, nutrients, carbon source pulse) are used to control gene expression, then gene expression can be induced, but side effects on physiology and gene expression occur that are deleterious to the experiment
Solution Approach 1:
The patent introduces a gratuitous inducer as an intermediary molecule that specifically binds to the transcription factor without triggering any physiological responses. This mediator allows precise control of the transcription factor while avoiding the harmful side effects of traditional perturbations like heat shock or carbon source changes.
Solution Approach 2:
The system separates the control mechanism into distinct modular components: a gratuitous inducer that only activates the transcription factor, and the transcription factor itself that controls only the target gene. This segmentation ensures that activation of one element does not trigger unwanted cascading effects on other physiological processes.
2Duration of action of stationary object
If tet-off system is used for target gene depletion, then transcription can be shut off, but protein elimination is slow due to long protein half-lives
Solution Approach 1:
The patent introduces a degradation signal (N-degron) at the amino terminus of the target protein in advance. This preliminary modification prepares the protein for rapid degradation, so that when the gratuitous inducer is applied and transcription is shut off, the existing protein is quickly eliminated by the proteasome rather than waiting for natural turnover.
3Productivity
If GAL4-mediated induction is used in S. cerevisiae, then target gene overexpression can be achieved, but cells must be grown in poor non-glucose carbon sources prior to galactose pulse
Solution Approach 1:
The patent replaces the complex carbon source switching requirement with a simple gratuitous inducer that can be added directly to glucose-containing media. The inducer acts as a disposable signal molecule that triggers transcription factor activation without requiring any changes to the growth medium or culture conditions, simplifying the操作流程.
4Adaptability or versatility
If GEV system is used for induction, then experiments can be conducted in glucose-containing media with beta-estradiol inducer, but the system only enables induction of gene expression, not protein depletion
Solution Approach 1:
The patent extends the GEV system to perform multiple functions: it can both induce gene expression (by activating transcription) and deplete target proteins (by inducing expression of a protease that degrades the tagged protein). This multi-functionality is achieved by adding a degradation signal to the target protein and using the same gratuitous inducer for both purposes.
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
Enables rapid, specific, and targeted protein degradation in yeast and eukaryotic cells, minimizing physiological effects and allowing for precise control of protein abundance, overcoming the limitations of existing systems like tet-off and GAL4-mediated induction.
Implementation Method 1
The transcriptional activator comprises a hormone-binding domain, wherein, when bound by a hormone the transcriptional activator induces transcription
Implementation Method 2
a protease-encoding gene that expresses a protease that is capable of hydrolyzing the target protein to yield a protein having an N-end rule destabilizing amino acid at the amino terminus
Implementation Method 3
the protease cleaves the target protein to expose the N-end rule destabilizing amino acid and the target protein is degraded
Data Source
AI summary
A system allows for rapid and specific induction of individual genes in eukaryotic cells using a chimeric transcriptional activator that is responsive to hormone inducer. Upon addition of the hormone, cytoplasmic transcriptional activator localizes to the nucleus and subsequently binds to promoters containing sequences that bind to its DNA-binding domain. Genetic modifications allow for rapid and specific degradation of a targeted protein upon addition of hormone by means of a regulated degron method that utilizes a protease variant. This system is useful for discovering new compounds by high throughput screening when introducing compound libraries to these protein-depleted cells.