Protein folding, aggregation and engineering

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The order of amino acids in a protein, i.e. the primary sequence, encodes how a protein folds into its functional "native" state, as well as how it may misfold to form nonfunctional and potentially toxic aggregates.  Despite extensive study, the molecular mechanisms by which primary sequence determines the inter-related properties of protein folding, structure, dynamics and function are far from being fully understood.  We are analyzing these properties at a detailed atomic level for proteins of biological, medical and biotechnological importance. Our experimental approach is to employ a battery of biochemical and biophysical techniques (such as molecular biological methods to express and engineer recombinant proteins, and multi-dimensional heteronuclear NMR spectroscopy, optical spectroscopies, chemical denaturation, calorimetry, mass spectrometry, light scattering and microscopy) to characterize the properties of natural and engineered proteins.       This proposal describes three projects: 1) folding and function of hisactophilin, an actin-bundling protein from the model organism, D. discoideum, and its human homolog, fascin.  These proteins have important roles in cell motility in biology and disease. We will study their molecular mechanisms of actin binding and reversible membrane binding, which are of fundamental biological importance.  We will also analyze molecular mechanisms of folding and of misfolding to form inclusion body aggregates, which are of interest for biotechnological applications and for understanding protein misfolding diseases; 2) molecular mechanisms of damage and aggregation of proteins due to sonication. These studies have important implications for many common applications of sonication in research, industry and medicine; and 3) folding and engineering of YchN-like proteins, to elucidate the determinants of secondary, tertiary and quaternary structure among related proteins, and mechanisms of protein structure evolution.  Our studies will provide fundamental insights into important characteristics of these proteins that will be applicable to the understanding, engineering and design of many other proteins.