Gabriel Rocco Sotero, BS
University of Delaware
Muropeptide Probes and Inhibitors to Interrogate SLC46 Transport in Innate Immunity
Bacterial muropeptides are unique ligands in innate immunity and have been linked with key inflammatory diseases of the skin such as psoriasis. The Silverman Laboratory has identified solute carriers (SLC) SLC46A2 and A3 as the respective transporters for the key muropeptides D-isoGlutamate-meso-diaminopimelic acid (iE-DAP) and muramyl dipeptide (MDP). Methotrexate (MTX) inhibits these transporters, preventing downstream immune responses; however, MTX is cytotoxic due to dihydrofolate reductase inhibition, motivating development of SLC46A-specific inhibitors. iE-DAP has been a long-standing synthetic challenge since its two stereocenters with identical chemical properties require C-C bond-forming reactions. While the Grubbs-cross-metathesis is the current most efficient path to construct the DAP carbon skeleton, a truly scalable route to this unique amino acid will allow for investigations into the broader roles of DAP-containing peptides in innate immunity. After optimizing the synthesis, we developed a library of iE-DAP-alkyne derivatives using click-conjugation with azide pharmacophores to probe substrate requirements and identify inhibitors for SLC46A2. Virtual screening of 190 compounds against a homology model of SLC46A2 identified potential candidates for in vitro evaluation in cell-based transport assays to probe inhibitory activity. Preliminary data suggest that disruption of a critical salt bridge in the transporter may be key to substrate requirement and inhibition
Bacterial muropeptides are unique ligands in innate immunity and have been linked with key inflammatory diseases of the skin such as psoriasis. The Silverman Laboratory has identified solute carriers (SLC) SLC46A2 and A3 as the respective transporters for the key muropeptides D-isoGlutamate-meso-diaminopimelic acid (iE-DAP) and muramyl dipeptide (MDP). Methotrexate (MTX) inhibits these transporters, preventing downstream immune responses; however, MTX is cytotoxic due to dihydrofolate reductase inhibition, motivating development of SLC46A-specific inhibitors. iE-DAP has been a long-standing synthetic challenge since its two stereocenters with identical chemical properties require C-C bond-forming reactions. While the Grubbs-cross-metathesis is the current most efficient path to construct the DAP carbon skeleton, a truly scalable route to this unique amino acid will allow for investigations into the broader roles of DAP-containing peptides in innate immunity. After optimizing the synthesis, we developed a library of iE-DAP-alkyne derivatives using click-conjugation with azide pharmacophores to probe substrate requirements and identify inhibitors for SLC46A2. Virtual screening of 190 compounds against a homology model of SLC46A2 identified potential candidates for in vitro evaluation in cell-based transport assays to probe inhibitory activity. Preliminary data suggest that disruption of a critical salt bridge in the transporter may be key to substrate requirement and inhibition
