UC San Diego

The overall theme of this dissertation is the application of mass spectrometry approaches to investigate infectious diseases. Chapter 1 contains background information regarding host-pathogen interactions, importance of clinical samples, and advances in mass spectrometry sample preparation, database curation, and data analysis techniques that familiarize the reader with the tools used during these studies. The following chapters describe primary author works completed by the author of this dissertation.Chapter 2 describes the discovery and characterization of microproteins produced by Staphylococcus aureus. The microproteins were discovered using a peptidogenomic approach and further validated with in-vitro and in-vivo assays. One of the novel microproteins is chemically and structurally similar to previously described virulence factors but appears to have a distinct mechanism of action. The other novel microprotein drives a dissociation phenotype reminiscent of exfoliative toxins. Elucidating the structural and biophysical mechanisms driving the interplay of these microproteins may provide a deeper understanding of host-pathogen interaction. Chapter 3 describes the application of multi-omics approaches to differentiate two similarly presenting enterococcal bacteremia subtypes and provides a global level view of the host immune and metabolic dysregulation. Using high resolution proteomics and metabolomics profiling of clinical serum samples we define a panel of over twenty biomarkers for further validation while also providing a number of targets of clinical importance.