The World Health Organization estimated that at the end of 2012 over 35 million individuals were infected with HIV-1 (Human Immunodeficiency Virus). Due to the advancements in highly active antiretroviral (HAART) therapy the number of AIDS-related deaths has been reduced and individuals are living longer. Despite successes with HAART, opportunistic infections remain one of major causes of death in AIDS patients. Among the most prevalent is the protozoal parasite pathogen, Cryptosporidium. Cryptosporidiosis is one of the AIDS- defining illnesses characterized by a severe chronic diarrhea for which there are currently no effective therapies and among the most frequent pathogens causing diarrheal diseases in developing countries. Efforts during the previous grant period have focused on a unique bifunctional enzyme thymidylate synthase-dihydrofolate reductase (TS-DHFR) found only in protozoal pathogens as a possible molecular target for inhibitor design. These proof of concept studies in Cryptosporidium hominis (Ch)TS-DHFR have identified unique species specific and allosteric/non-active target regions in this bifunctional enzymes and mutational analysis and mechanistic studies have validated these sites as essential for catalytic function. The PIs lab and their collaborators have developed a distinctive and successful computationally and mechanistically guided approach for the discovery of new inhibitors of ChTS-DHFR. This partnership of computational and detailed experimental methodologies is a unique strategy that builds optimal physiochemical and pharmacological parameters into the design. These molecules are then experimentally tested and the design iteratively refined through mechanistic, structural and cellular evaluation. Molecular docking and virtual screening coupled with structural analyses have discovered novel inhibitors of CH TS-DHFR including some with nanomolar potency and anti-Cryptosporidial activity in cell culture. The current grant period will focus on lead optimization and a novel nanotechnology strategy for parasite drug delivery to develop new therapies to treat Cryptosporidial infections.
Opportunistic infections are the primary cause of suffering and death in individuals with AIDS. Many of these infections are produced by parasites that rarely affect individuals who are not immunocompromised. Unfortunately, successful combination therapies against the HIV-1 virus still leave most patients susceptible to opportunistic parasitic infections and new therapies are desperately needed.
|Anderson, Karen S (2017) Understanding the molecular mechanism of substrate channeling and domain communication in protozoal bifunctional TS-DHFR. Protein Eng Des Sel 30:253-261|
|Mukerjee, Anindita; Iyidogan, Pinar; Castellanos-Gonzalez, Alejandro et al. (2015) A nanotherapy strategy significantly enhances anticryptosporidial activity of an inhibitor of bifunctional thymidylate synthase-dihydrofolate reductase from Cryptosporidium. Bioorg Med Chem Lett 25:2065-7|
|Kumar, Vidya P; Cisneros, Jose A; Frey, Kathleen M et al. (2014) Structural studies provide clues for analog design of specific inhibitors of Cryptosporidium hominis thymidylate synthase-dihydrofolate reductase. Bioorg Med Chem Lett 24:4158-61|
|Sharma, Hitesh; Landau, Mark J; Sullivan, Todd J et al. (2014) Virtual screening reveals allosteric inhibitors of the Toxoplasma gondii thymidylate synthase-dihydrofolate reductase. Bioorg Med Chem Lett 24:1232-5|
|Landau, Mark J; Sharma, Hitesh; Anderson, Karen S (2013) Selective peptide inhibitors of bifunctional thymidylate synthase-dihydrofolate reductase from Toxoplasma gondii provide insights into domain-domain communication and allosteric regulation. Protein Sci 22:1161-73|
|Kumar, Vidya P; Frey, Kathleen M; Wang, Yiqiang et al. (2013) Substituted pyrrolo[2,3-d]pyrimidines as Cryptosporidium hominis thymidylate synthase inhibitors. Bioorg Med Chem Lett 23:5426-8|
|Sharma, Hitesh; Landau, Mark J; Vargo, Melissa A et al. (2013) First three-dimensional structure of Toxoplasma gondii thymidylate synthase-dihydrofolate reductase: insights for catalysis, interdomain interactions, and substrate channeling. Biochemistry 52:7305-7317|
|Zaware, Nilesh; Sharma, Hitesh; Yang, Jie et al. (2013) Discovery of potent and selective inhibitors of Toxoplasma gondii thymidylate synthase for opportunistic infections. ACS Med Chem Lett 4:1148-1151|
|Martucci, W Edward; Rodriguez, Johanna M; Vargo, Melissa A et al. (2013) Exploring novel strategies for AIDS protozoal pathogens: ?-helix mimetics targeting a key allosteric protein-protein interaction in C. hominis TS-DHFR. Medchemcomm 4:|