Our group aims to explore the function and physiological role of novel enzymes and lipids involved in the development of neurological diseases and cancer. To achieve these goals, we propose to bridge chemical, analytical, and biological approaches to identify novel disease targets and develop chemical approaches for therapeutic intervention. Our expertise in cell and molecular biology, chemical probes, mass spectrometry, and imaging technologies presents a unique opportunity for broad training in chemical biology. This multidisciplinary approach will rely on technological innovation focused on unexplored biochemical pathways and their links to human disease.
Cysteine residues in proteins have pKa values close to neutral and are often in their reactive thiolate form in cells, making them nucleophilic and targets of distinct post-translational modifications. One such modification, termed protein S-palmitoylation describes the thioester linkage of palmitic acid and cysteine in proteins, and is required for membrane association and spatial regulation of diverse cellular pathways involved in cell growth and signaling. In many cases, palmitoylation is thought to be dynamically regulated, although the mechanisms that control this lipid modification remain poorly characterized. In order to understand the processes regulating dynamic palmitoylation, we have developed a quantitative chemo-proteomic platform for global comparative analysis of palmitoylated proteins, and used this platform to interrogate the population of palmitoylated proteins regulated by both palmitoyl transferases and thioesterases implicated in cancer and neurological diseases. Additionally, using competitive activity-based high throughput screening, we identified a new class of mechanism-based in vivo potent and highly selective inhibitors to enzymes proposed to regulate protein palmitoylation. In combination with novel activity-based probes, we identified a unique subset of enzymatically regulated, dynamically palmitoylated proteins in cells.
Understanding the functional role of dynamic palmitoylation in disease will be explored through the application of new inhibitors and genetic models to test the importance of potential therapeutic targets in vitro and in vivo. Additionally, these methodologies will be used to assign substrates to palmitoyl transferases and thioesterases, as well as the introduction of new fluorescence microscopy approaches for visualizing the spatial and temporal control of membrane compartmentalization. Furthermore, through the development of an expanded suite of chemical probes, we will explore the enzymology, regulation, interactions, and function of novel enzymes involved in the biosynthesis and degradation of unique lipids altered in specific disease states.
Li Y, Martin BR, Cravatt BF, and Hofmann SL. DHHC5 palmitoylates flotillin-2 and is rapidly degraded on induction of neuronal differentiation in cultured cells. J. Biol. Chem., In Press Nov. 11, 2011.
Martin BR*, Wang C, Adibekian A, Tully SE, and Cravatt BF*. Global Profiling of Dynamic Protein Palmitoylation. Nature Methods, Advanced Online Publication Nov. 6, 2011. * Corresponding authors.
Adibekian A, Martin BR, Wang C, Hsu KL, Bachovchin DA, Niessen S, Hoover H, and Cravatt BF. Click-generated triazole ureas as ultrapotent, in vivo-active serine hydrolase inhibitors. Nature Chemical Biology. In press. (2011).
Ladygina N, Martin BR, Altman A. T-cell responsiveness and anergy by reversible palmitoylation. Advances in Immunology. In press. (2011).
Martin BR, Cravatt BF. Large-scale profiling of protein palmitoylation in mammalian cells. Nature Methods. 2009 Feb;6(2):135-8.
Martin BR, Deerinck TJ, Ellisman MH, Taylor SS, Tsien RY. Isoform-specific PKA dynamics revealed by dye-triggered aggregation and DAKAP1alpha-mediated localization in living cells. Chemistry & Biology. 2007 Sep;14(9):1031-42
Martin BR, Giepmans BN, Adams SR, Tsien RY. Mammalian cell-based optimization of the biarsenical-binding tetracysteine motif for improved fluorescence and affinity. Nature Biotechnology. 2005 Oct;23(10):1308-14.
Adams SR, Campbell RE, Gross LA, Martin BR, Walkup GK, Yao Y, Llopis J, Tsien RY. New biarsenical ligands and tetracysteine motifs for protein labeling in vitro and in vivo: synthesis and biological applications. J Am Chem Soc. 2002 May 29;124(21):6063-76.