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Updated: Feb 10, 2026
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Mutagenesis and Functional Selection Protocols for Directed Evolution of Proteins in E. coli
Published on: March 16, 2011
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Biophysical constraints determine the selection of phenotypic fluctuations during directed evolution
Hong-Yan Shih1, Harry Mickalide1, David T Fraebel1
1Department of Physics and Center for the Physics of Living Cells, Loomis Laboratory of Physics, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, IL 61801, United States of America.
Physical Biology
|May 16, 2018
Summary
Directed evolution experiments can reduce phenotypic variation in bacterial populations. This study investigates how selection constraints impact this reduction, offering insights into adaptation and evolution.
Area of Science:
- Evolutionary Biology
- Genetics
- Microbiology
Background:
- Phenotypic fluctuations, or variation within and between individuals, are common across all life forms.
- These fluctuations can be a source of adaptive potential and are subject to evolutionary selection pressures.
- Understanding how selection shapes these variations is crucial for comprehending evolutionary dynamics.
Purpose of the Study:
- To investigate the impact of constraints on phenotypic fluctuations during directed evolution.
- To determine the genetic basis for changes in phenotypic variation under selection.
- To develop a general model for the evolution of phenotypic fluctuations under constraints.
Main Methods:
- Experimental evolution of bacterial populations selected for enhanced migration.
- Genetic sequencing and engineering to identify the genetic underpinnings of phenotypic variation.
- Development of an abstracted numerical simulation model to generalize findings.
Main Results:
- Bacterial populations selected for faster migration exhibited reduced cell-to-cell phenotypic variation.
- Genetic analysis revealed specific mechanisms driving this reduction in variation.
- Numerical simulations indicated that selection strength and phenotypic bounds influence variation dynamics, with potential for both increase and decrease.
Conclusions:
- Directed evolution under constraints can lead to a significant decrease in phenotypic fluctuations.
- The study provides a framework for understanding how selection shapes variation, with implications for evolutionary trajectories.
- Further research is suggested to explore diverse parameters and their effects on evolutionary outcomes.
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