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Resurrecting ancestral alcohol dehydrogenases from yeast
J Michael Thomson1, Eric A Gaucher, Michelle F Burgan
1Department of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610, USA.
Nature Genetics
|May 3, 2005
Summary
Researchers resurrected an ancient yeast enzyme, Adh(A), revealing it was optimized for ethanol production, not consumption. This suggests early yeast recycled NADH rather than storing ethanol for later use.
Area of Science:
- Biochemistry
- Evolutionary Biology
- Systems Biology
Background:
- Modern yeast produce ethanol via pyruvate and acetaldehyde using alcohol dehydrogenase 1 (Adh1).
- A related enzyme, Adh2, allows yeast to consume accumulated ethanol.
- Accumulated ethanol may serve as a defense mechanism for yeast in fruit environments.
Purpose of the Study:
- To resurrect and characterize the ancestral enzyme Adh(A), the common ancestor of Adh1 and Adh2.
- To understand the ancestral function of Adh(A) in relation to ethanol metabolism.
- To infer the evolutionary history of Adh1-Adh2 duplication and its ecological context.
Main Methods:
- Resurrection of the ancestral Adh(A) enzyme.
- Kinetic analysis of Adh(A) activity.
- Silent nucleotide dating to estimate evolutionary divergence times.
Main Results:
- The resurrected Adh(A) enzyme showed optimal activity for ethanol production, not consumption.
- Kinetic data supports the hypothesis that ancestral yeast used Adh(A) for NADH recycling during glycolysis.
- Silent nucleotide dating places the Adh1-Adh2 gene duplication around the Cretaceous period, coinciding with the rise of fleshy fruits.
Conclusions:
- The ancestral yeast enzyme Adh(A) was primarily involved in ethanol synthesis for metabolic purposes, not storage.
- The Adh1-Adh2 duplication event was linked to ecological changes, specifically the evolution of fleshy fruits.
- This study provides insights into the co-evolution of enzymes and ecosystems, contributing to planetary systems biology.