title: Exploring the Trypanosoma brucei Hsp83 potential as a target for structure guided drug design.
abstract: Human African trypanosomiasis is a neglected parasitic disease that is fatal if untreated. The current drugs available to eliminate the causative agent Trypanosoma brucei have multiple liabilities, including toxicity, increasing problems due to treatment failure and limited efficacy. There are two approaches to discover novel antimicrobial drugs--whole-cell screening and target-based discovery. In the latter case, there is a need to identify and validate novel drug targets in Trypanosoma parasites. The heat shock proteins (Hsp), while best known as cancer targets with a number of drug candidates in clinical development, are a family of emerging targets for infectious diseases. In this paper, we report the exploration of T. brucei Hsp83--a homolog of human Hsp90--as a drug target using multiple biophysical and biochemical techniques. Our approach included the characterization of the chemical sensitivity of the parasitic chaperone against a library of known Hsp90 inhibitors by means of differential scanning fluorimetry (DSF). Several compounds identified by this screening procedure were further studied using isothermal titration calorimetry (ITC) and X-ray crystallography, as well as tested in parasite growth inhibitions assays. These experiments led us to the identification of a benzamide derivative compound capable of interacting with TbHsp83 more strongly than with its human homologs and structural rationalization of this selectivity. The results highlight the opportunities created by subtle structural differences to develop new series of compounds to selectively target the Trypanosoma brucei chaperone and effectively kill the sleeping sickness parasite.
authors.affiliation: The Structural Genomics Consortium (SGC), University of Toronto, Toronto, Ontario, Canada ; Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, United States of America.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Pizarro
authors.forename: Tanya
authors.initials: T
authors.lastname: Hills
authors.forename: Guillermo
authors.initials: G
authors.lastname: Senisterra
authors.forename: Amy K
authors.initials: AK
authors.lastname: Wernimont
authors.forename: Claire
authors.initials: C
authors.lastname: Mackenzie
authors.forename: Neil R
authors.initials: NR
authors.lastname: Norcross
authors.forename: Michael A J
authors.initials: MA
authors.lastname: Ferguson
authors.forename: Paul G
authors.initials: PG
authors.lastname: Wyatt
authors.forename: Ian H
authors.initials: IH
authors.lastname: Gilbert
authors.forename: Raymond
authors.initials: R
authors.lastname: Hui
mesh_terms: D000981:Antiprotozoal Agents / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D055808:Drug Discovery / Q000379:methods*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D021261:Parasitic Sensitivity Tests; D011485:Protein Binding; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000187:drug effects* / Q000201:enzymology* / Q000254:growth & development
chemical_list: D000981:Antiprotozoal Agents; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C490310:Hsp83 protein, protozoan; D015800:Protozoan Proteins