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Comprehensive analysis of fitness effects and epistasis along a billion-year evolutionary trajectory

十亿年进化轨迹上的适应度效应和上位性综合分析

基本信息

批准号：
10643977
负责人：
DANIEL N BOLON
金额：
$ 54.98万
依托单位：
UNIVERSITY OF CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-06-01 至 2025-03-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10643977
关键词：
Accidents Affect Amino Acid Sequence Amino Acids Animals Architecture Biochemical Biological Assay Biological Models Biological Process Biophysical Process Biophysics Catalysis Cells Chemicals Client Complement Conserved Sequence Data Disease Engineering Enzymes Eukaryota Eukaryotic Cell Event Evolution Future Genes Genetic Genetic Epistasis Genetic Variation Health Human Knowledge Lead Libraries Ligand Binding Measures Mediating Methods Molecular Chaperones Molecular Conformation Molecular Evolution Mutation Outcome Pattern Phylogenetic Analysis Phylogeny Play Process Property Protein Engineering Proteins Public Health Recording of previous events Resolution Role Saccharomyces cerevisiae Sampling Shapes Signal Transduction Site Structure Structure-Activity Relationship System Techniques Technology Time Work Yeasts biological systems biophysical properties experimental analysis experimental study fitness fungus gene therapy improved insight mutant mutation screening new technology prevent protein folding reconstruction sample fixation tool

项目摘要

Epistatic interactions within proteins can, in principle, make the paths and outcomes of evolution contingent on chance events; they can also entrench proteins with residues that appear to be optimal but are accidents of history. The extent to which epistasis actually affected the trajectory and outcomes of molecular evolution depends on the fitness effects of substitutions when they occurred in history compared to their potential effects earlier or later in time and on the temporal order in which interacting substitutions occurred. Deep mutational scanning studies have revealed pervasive epistasis among the huge number of possible mutations, but no studies have directly assessed how the fitness effects of substitutions that happened during history changed over time as the protein evolved. We will perform the first comprehensive experimental analysis of the fitness effects of all amino acid states that evolved in a protein during a long-term phylogenetic trajectory, both at the time they occurred and if they had occurred at other points in history. These data will be analyzed in the ordered temporal context of the protein's phylogeny and supplemented with biochemical experiments, enabling a deep characterization of the causes and consequences of epistasis, contingency and entrenchment across the billion-year history of an essential protein. Our model system is ideal for this purpose. Hsp90, the essential molecular chaperone in all eukary- otic cells, plays key roles in protein folding and maturation, cell signaling, and a wide range of diseases. Strong phylogenetic signal allows confident reconstruction of the billion-year evolutionary history of Hsp90's protein sequence from the last common ancestor of animals, fungi and related protists to present-day Saccharomyces cerevisiae. We will generate targeted protein libraries containing every ancestral and derived state that occurred during this phylogenetic trajectory, singly and in every possible pair, in the background of all 30 reconstructed ancestral proteins along the trajectory. Using a high- resolution bulk competition assay in yeast, we will precisely measure selection coefficients and epistatic interactions and quantify how these properties changed over time. This will reveal the fitness effects and interactions of every substitution at the approximate time it occurred, as well as the effects and interactions it would have had if it happened (or reverted to the ancestral state) at any point earlier or later during the trajectory. We will also apply biophysical and structural techniques to elucidate the underlying biochemical mechanisms that drove these genetic and evolutionary phenomena. This work will provide deep new insight into the ways in which proteins' genetic and physical architecture influences, and is influenced by, the processes by which they evolve; it will also strengthen our understanding of sequence-structure-function relationships in a biologically essential protein.

原则上，蛋白质内部的上位相互作用可以决定进化的路径和结果