Related Experiment Video
Updated: May 26, 2026
10:50
Directed Evolution Method in Saccharomyces cerevisiae: Mutant Library Creation and Screening
Published on: April 1, 2016
Engineered NADH-dependent GRE2 from Saccharomyces cerevisiae by directed enzyme evolution enhances HMF reduction
1Bioenergy Research Unit, National Center for Agricultural Utilization Research, USDA-ARS, 1815 North University Street, Peoria, IL 61604, USA.
Enzyme and Microbial Technology
|January 10, 2012
Summary
Engineered yeast strains with modified GRE2 genes show enhanced tolerance to lignocellulosic inhibitors like furfural and HMF. These improved Saccharomyces cerevisiae strains can better detoxify these compounds, facilitating more efficient biomass fermentation.
Area of Science:
- Biotechnology
- Synthetic Biology
- Enzyme Engineering
Background:
- Furfural and 5-hydroxymethylfurfural (HMF) are key inhibitors produced during lignocellulosic biomass pretreatment.
- These inhibitory compounds hinder microbial growth and fermentation processes.
- Saccharomyces cerevisiae possesses aldehyde reductases that can detoxify these inhibitors, but native activity is often insufficient.
Purpose of the Study:
- To enhance the in situ detoxification capabilities of Saccharomyces cerevisiae against furfural and HMF.
- To engineer the GRE2 gene encoding an aldehyde reductase for improved activity and cofactor utilization.
- To develop yeast strains with increased tolerance to lignocellulosic-derived inhibitors for improved biofuel production.
Main Methods:
- Directed enzyme evolution was applied to the GRE2 gene (YOL151W) of Saccharomyces cerevisiae.
- Specific amino acid substitutions were introduced to create mutant strains Y62-C11 and Y62-G6.
- Enzyme activity assays using NADH and NADPH were performed on crude cell extracts and partially purified proteins.
Main Results:
- Mutant strains Y62-C11 and Y62-G6 exhibited faster growth rates and improved viability under 30 mM HMF stress compared to wild-type.
- Crude extracts of mutants showed 3- to 4-fold (HMF) and 3- to 9-fold (furfural) increased specific activity with NADH.
- Mutant Y62-G6 demonstrated significantly enhanced reductase activity with NADPH (13-fold for HMF, 15-fold for furfural).
- Site-directed mutagenesis confirmed that the Asp285 substitution in Y62-G6 is crucial for increased NADPH-dependent activity.
Conclusions:
- Directed evolution of GRE2 successfully generated Saccharomyces cerevisiae mutants with enhanced aldehyde reductase activity.
- The engineered strains exhibit improved tolerance to furfural and HMF, crucial for lignocellulosic fermentation.
- The identification of Asp285 as key for NADPH utilization opens avenues for further enzyme engineering for biofuel applications.
Related Concept Videos
01:22Bioreactor Controls-III
Strain improvement is a foundational strategy in industrial microbiology aimed at maximizing microbial productivity, particularly because natural isolates typically yield commercially valuable products in very low concentrations. Although optimizing the culture medium and environmental conditions can improve yields, these adjustments are inherently limited by the organism’s genetic potential. As a result, the focus shifts toward genetic modifications to enhance biosynthetic capacity. The...
01:29Role of Reduced Coenzymes NADH and FADH₂
The energy released from the breakdown of the chemical bonds within nutrients can be stored either through the reduction of electron carriers or in the bonds of adenosine triphosphate (ATP). In living systems, a small class of compounds functions as mobile electron carriers, molecules that bind to and shuttle high-energy electrons between compounds in pathways. The principal electron carriers that will be considered originate from the B vitamin group and are derivatives of nucleotides; they are...
01:24Other Glycolytic Pathways
The pentose phosphate pathway (PPP) operates in parallel with glycolysis, facilitating the metabolism of both pentoses and glucose. This pathway consists of two distinct phases: the oxidative and non-oxidative phases. While it does not directly generate ATP, the intermediates formed during the process can integrate into glycolysis, contributing to cellular energy metabolism when required.Oxidative Phase: NADPH ProductionThe oxidative phase of the pentose phosphate pathway is primarily...
01:24Evolution of New Traits in Microbes
Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
01:19Oxidation and Reduction of Organic Molecules
Energy production within a cell involves many coordinated chemical pathways. Most of these pathways are combinations of oxidation and reduction reactions, which occur at the same time. An oxidation reaction strips an electron from an atom in a compound, and the addition of this electron to another compound is a reduction reaction. Because oxidation and reduction usually occur together, these pairs of reactions are called redox reactions.
The removal of an electron from a molecule, results in a...
The removal of an electron from a molecule, results in a...