Structural and biochemical studies of proteins implicated in oxidative stress

The parkinsonism protein DJ-1, a product of PARK7, causes early-onset autosomal-recessive Parkinson\u27s disease. The importance of DJ-1 in mitochondrial dynamics and neurodegeneration has highlighted its function as a component of the Parkin/PINK1 system in maintaining mitochondrial health and signaling, as discussed in Chapter 2. Additionally, DJ-1 has been connected to not only neuronal survival, but has also been implicated in a variety of diseased states, from cancer to cardiac ischemia as discussed in Chapter 3, although a clear function for DJ-1 has not yet been attributed. Structural conservation of proteins through billions of years is strongly indicative of functional conservation. YajL is the closest prokaryotic homolog of DJ-1, sharing many of the conserved structural elements believed to be key in DJ- 1\u27s function, such as the oxidation-prone Cysteine 106. The impact of using YajL to investigate the conserved functions of DJ-1 in a prokaryotic model is discussed in Chapter 4. Using this system, it was possible to test the hypothesis where YajL, and by extension, DJ-1, could be direct detoxifiers of reactive oxygen species; the extent of structural similarity between DJ-1 and YajL makes YajL an attractive model system to explore the functions of DJ-1 in a prokaryotic context. Finally, in Chapter 5, the structure of the prokaryotic protein YaaA is described for the first time. YaaA, believed to be involved in bacterial stress defense, is an uncharacterized member of the DUF328 superfamily and is regulated by OxyR. Chapter 5 discusses the biophysical characterization of YaaA beginning with its crystal structure- solved to 1.65 Å- and a proposed function in DNA-binding