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Updated: May 10, 2026
12:48
The Multifaceted Benefits of Protein Co-expression in Escherichia coli
Published on: February 5, 2015
Substrate ambiguous enzymes within the Escherichia coli proteome offer different evolutionary solutions to the same
Sylvia Hsu-Chen Yip1, Ichiro Matsumura
1Department of Biochemistry, Center for Fundamental and Applied Molecular Evolution, Rollins Research Center, Emory University School of Medicine, USA.
Molecular Biology and Evolution
|June 4, 2013
Summary
Enzymes with ambiguous substrate activity can evolve new functions. Different proteins with the same ambiguous activity evolved distinct solutions to a phosphoserine phosphatase (PSP) problem, demonstrating proteome adaptability.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Enzymes can possess substrate ambiguity, offering a basis for evolving new catalytic functions.
- Previous work identified three proteins (Gph, HisB, YtjC) that suppress a specific genetic deletion in E. coli.
Purpose of the Study:
- To investigate if different proteins with the same substrate-ambiguous activity evolve distinct mechanisms under identical selection pressures.
- To characterize the evolutionary adaptations of Gph, HisB, and YtjC for enhanced phosphoserine phosphatase (PSP) activity.
Main Methods:
- Directed evolution of Gph, HisB, and YtjC variants for improved complementation of a ΔserB E. coli strain.
- Biochemical characterization of evolved amino acid changes on PSP activity and kinetics.
- Analysis of epistasis between mutations.
Main Results:
- Gph and HisB, despite belonging to the same hydrolase superfamily, evolved distinct biochemical mechanisms.
- Most beneficial mutations were effective in isolation, but showed antagonistic epistasis when combined.
- One mutation (N102T in YtjC) showed sign epistasis, being detrimental alone but beneficial in combination.
- A specific mutation in the chromosomal copy of hisB was sufficient for suppression.
Conclusions:
- Proteomes can provide multiple mechanistic solutions to molecular recognition challenges.
- Enzyme evolution from substrate-ambiguous precursors is a viable pathway for generating novel functions.
- Understanding epistasis is crucial for predicting the outcomes of evolutionary trajectories.
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