Every eukaryotic cell contains a copy of the genome in its nucleus, but only a subset of genes is turned on in any given cell at any given time. Proper regulation of genes is critical in development and basic biological function from the cellular to organismal level. The eukaryotic genome exists in complex with proteins called histones. The histone/DNA complex is called chromatin and is composed of repeating subunits called nucleosomes. Each nucleosome looks like a spool wrapped with string in which the histones form the spool and a segment of genomic DNA is the string. It is the way in which the DNA wraps the histone core (called nucleosome structure) and the organization of the nucleosomes with respect to each other that allows or restricts access to the underlying genome, determining patterns of gene expression. This project addresses the fundamental questions of how patterns of small chemical tags, termed post-translational modification (PTM), are read-out by other proteins associated with chromatin (called co-factors) and how this association may alter nucleosome structure to affect precise regulation of downstream events. Nuclear magnetic resonance (NMR) spectroscopy will be used to study a variety of nucleosome constructs to determine how a specific model transcription factor associates with a nucleosome containing different patterns of PTMs and how this association alters the nucleosome structure and its dynamic behavior at atomic resolution.
This project supports the education and training of undergraduate and pre-and post-doctoral students both in the classroom via courses instructed by the PI, as well as in the laboratory in which they will carry out the project goals. In addition, the research team will partner with the Iowa-based non-profit organization, the Workplace Learning Connection, to establish an internship program in the laboratory for high school students. Students in from Iowa City and surrounding counties will gain 45-90 hours of laboratory experience, working on various aspects of the project for which they will receive high school credit. This program will provide students with a tangible research experience in the basic sciences, and will also allow the PI to establish mentoring relationships with them that are expected to last well beyond their time in the laboratory. The investigator will continue these activities to contribute towards increased participation in STEM areas, which is imperative for the growth and stability of the United States economy as well as our global competitiveness.
The main objective of the proposed research is to understand the fundamental and biologically important mechanisms by which histone post-translational modifications (PTMs) regulate chromatin structure. The investigator and her students will utilize NMR spectroscopy and other biochemical and biophysical methods to investigate the interaction of a model system, the BPTF PHD-finger-Bromodomain motif with modified nucleosomes. The investigators hope to understand, in detail, how a multi-domain motif recognizes PTMs at the level of the nucleosome, especially how distinct patterns of PTMs across multiple histone tails are specifically read out. In addition, through measurement of NMR relaxation parameters, they will address the important questions of how histone modifications and effector domain binding regulate the conformational dynamics of the nucleosome, likely stabilizing or destabilizing conformational states that may be essential for downstream function. This research will be fully integrated with a plan for education outreach, focused on sparking interest of high school students in STEM fields.
