The overarching theme of this project is to develop a fundamental understanding of functional oligomerization of proteins and its relation to protein aggregation. When proteins acquire a destabilizing mutation that thermodynamically or kinetically impairs their folding they often aggregate in cytoplasm which leads to deleterious consequences for an organism. Functional oligomerization is a newly discovered mechanism by which destabilized proteins avoid aggregation by forming specific highly active and soluble dimers or in rare cases higher order oligomers. This mechanism plays a key role in providing high fitness escape route in response to potentially deleterious destabilizing mutations or dangerous variations of the environment. This project will provide a fully atomistically resolved insight into plasticity of protein structure and function in response to mutations and changing environments. This study focuses on an essential enzyme, Dihydrofolate Reductase, (DHFR) whose destabilized mutants were found to form soluble functional dimers in E. Coli at elevated temperature. The PI will develop advanced computational tools to predict possible structures and thermodynamic stabilities of oligomers formed by mutant forms of DHFR and formulate hypotheses of domain swap mechanisms, which will be tested by mutagenesis experiments. The mutations, which switch between functional oligomerization and non-functional aggregation will be identified and their effect on protein stability and cellular fitness will be experimentally tested. Finally, the structures of soluble oligomers will be determined using NMR technique to provide a feedback for evaluation and improvement of simulation techniques and force-fields.
The computational and experimental tools developed in this work will allow researchers to study adaptation through oligomerization in other systems of Biological interest. Since this project encompasses a broad range of approaches and techniques, from computational studies to experimental research in vitro and in vivo, postdocs, graduate and undergraduate students will receive broad training. The evolutionary implications of this research are significant and will be communicated to general public through a series of public lectures on molecular foundations of evolution, raising the scientific literacy and appreciation of the excitement of scientific research at the frontiers of human knowledge. More generally this research will have direct impact on environmental and agricultural studies by advancing our mechanistic molecular level understanding of how proteomes of microorganisms adjust to changing environments. This project is being jointly supported by the Molecular Biophysics Cluster in the Division of Molecular and Cellular Biosciences and the Physics of Living Systems program in the Physics Division.
