The Serine Hydrolases of Drosophila melanogaster: Integrated Chemoproteomics and Genetics

Abstract

The serine hydrolase (SH) superfamily is one of the largest functional enzyme classes across all life forms and consists of proteases, peptidases, lipases, and carboxylesterases. Since very little is known about the SH family in Drosophila melanogaster (fruit fly), my Ph.D. worked focused on broadly assigning biochemical functions to various unannotated members of this superfamily in flies. Initially, using a bioinformatics approach, I collated an exhaustive list of SH enzymes in flies, and leveraging the functional proteomics strategy called “chemoproteomics”, I generated an activity atlas of all the SH enzymes that are expressed during different development stages in flies, and across various anatomical regions in an adult fly. Next, I tested the activities of various SH enzymes during an infection paradigm in flies, and identified ~10 SHs modulated on infection. One of these is an uncharacterized enzyme CG17192, a putative lipase whose activity is differentially regulated upon infection. Using complementary genetics, biochemical and LC-MS based lipidomics studies, I show that CG17192 functions as phospholipase, with preference for phosphatidylserine and phosphatidylinositol as in vivo substrates for this enzyme. My studies possibly place CG17192 as an important regulator of inter-organ crosstalk and signaling events and show the power of using an integrated approach towards understanding in vivo enzyme functions in physiological settings. Also, I generated reagents using cloning, protein expression antibody generation, CRISPR/cas9 based knockouts flies for the annotation of target SHs.