RAS/cAMP/PKA Pathway Mutations for Yeast Fermentation Efficiency

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Solution Overview

Problem

Recombinant yeast strains used in ethanol production often exhibit undesirable phenotypes such as poor ethanol tolerance and high residual sugar during yeast propagation, which affects fermentation efficiency.

Innovation Solution

Yeast cells are selected or genetically engineered to enhance signaling activity in the RAS/cAMP/PKA pathway, specifically through mutations in Ras1, Ras2, Ira1, and Ira2 proteins, to improve fermentation efficiency while maintaining propagation efficiency at high cell densities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If recombinant yeast strains are used to improve fermentation efficiency, then ethanol production increases, but propagation efficiency deteriorates due to poor ethanol tolerance and high residual sugar

Engineering Contradiction:

Improveethanol productionVSAvoidpropagation efficiency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by modifying the RAS/cAMP/PKA signaling pathway parameters through mutations in Ras1, Ras2, Ira1, and Ira2 proteins. These genetic modifications alter the signaling pathway's activity level, enabling the yeast to maintain high fermentation productivity while preserving propagation efficiency by regulating the pathway's activation state during different growth phases

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention implements dynamics by creating a conditionally active signaling pathway that responds to environmental cues. The mutated Ras and Ira proteins enable dynamic regulation where the RAS/cAMP/PKA pathway is activated during fermentation to enhance ethanol production but remains controlled during propagation to maintain cell density and viability

Inventive Principle:

Principle #15Dynamics

2Productivity

If yeast propagation is conducted at high cell density to improve productivity, then fermentation capacity increases, but undesirable phenotypes appear including poor ethanol tolerance and high residual sugar

Engineering Contradiction:

Improvefermentation capacityVSAvoidresidual sugar

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements feedback mechanisms through the RAS/cAMP/PKA signaling pathway, which responds to cellular metabolic states. The mutated Ira1 and Ira2 proteins provide negative feedback regulation that prevents excessive pathway activation, allowing the yeast to efficiently consume sugars during high-density fermentation while maintaining ethanol tolerance and avoiding accumulation of residual sugar

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11667680B2Regulation of the RAS/cAMP/PKA signaling pathway in yeasts for obtaining a fermentation product during fermentation

Publication Date: 2023.06.06 DANSTAR FERMENT AG

AI summary

The present disclosure relates to the modulation in the RAS/cAMP/PKA signaling pathway for maintaining the propagation efficiency and increasing fermentation efficiency of yeast cells. The present disclosure provides yeast cells having or engineered to exhibit a modulation in signaling in a RAS/cAMP/PKA pathway, depending on conditions. For example the yeast cells can be selected or genetically modified to express a mutated Ras1 protein, a mutated Ras2 protein, a mutated Ira1 protein and/or a mutated Ira2 protein, optionally in combination with specific promoters. Also provided herewith are methods for propagating the yeast cells as well as using the yeast cells to generate a fermented product (such as ethanol).