UC Merced

Intrinsically disordered protein regions (IDRs) play a variety of essential roles in regulating cellular function. Instead of folding into a single stable structure, an IDR exists in an ensemble of interconverting conformations biased by local and long-range intramolecular interactions. The absence of a fixed 3D structure combined with high solvent accessibility makes IDRs sensitive to changes in their physical-chemical surroundings. This dissertation describes investigations related to the ability of IDRs to sense and respond to changes in their surrounding solution conditions, and proposes a new paradigm of IDRs as sensors of cellular physicochemistry. Chapter 1 introduces the concept of IDRs as physicochemical sensors. Chapter 2 describes a project in which I developed a pipeline to allow medium-throughput FRET assays of IDR global dimensions in a wide variety of solution conditions, as well as benchmarking and analytical tools to allow meaningful comparison of the behavior of diverse IDRs, and used this system to characterize the end-to-end distance and solution sensitivity of several naturally-occurring IDRs. Chapter 3 describes a project in which my colleague and I performed parallel assays on naturally-occurring and synthetic IDRs in vitro and in live cells to test whether structural biases and sensitivity seen in vitro would be preserved when the same IDRs were tested in live cells. Chapter 4 describes a bioengineering project in which we used the systems described in Chapters 2 and 3 to contribute to the design and testing of a novel IDR-based biosensor that can monitor osmotic stress in live cells. Chapter 5 concludes the dissertation and suggests directions for further research.